Part B - Demand, Condition, Capacity, and Interdependence

EAM.4 - Assess Demand and Service Need for Asset Decisions

Type: Method Status: Stable

EAM.4:1 - Problem frame

Use this pattern when an asset choice depends on how much service will be needed, where and when. Average demand can fit current capability while a seasonal peak, protected service group or changing use makes an option inadequate.

Begin with the service question and distinguish current commitments from forecasts. Return the demand scenarios and requirements needed to compare asset options. If an existing demand assessment answers the question at the relevant boundary and period, use it. Construct a new account when its missing basis could change the asset choice.

EAM.4:2 - Problem

Demand totals hide timing, location and service differences. Forecasts can be treated as commitments, while existing commitments can be dismissed as optional scenarios. Even plausible forecasts may conceal which observation, population or loss allowance produced the number. A large forecast model can also obscure a simple known shortfall.

EAM.4:3 - Forces

Underestimating demand can leave service inadequate; overestimating it can commit resources to unnecessary capacity. Better forecasts cost time and data work. Uncertainty matters through the options or claims it could change, not merely through the width of a reported interval. A useful component account must preserve the period and boundary in which its quantities can be combined.

EAM.4:4 - Solution

EAM.4:4.1 - Fix the service question and reuse an adequate answer

Identify the service result, recipients and relevant horizon. State the quantity and quality required, its timing and location, and the source and authority of any commitment. OPS.1 can supply the operating service and commitment account.

Separate an authorized requirement from a forecast of use. A known seasonal commitment can be compared directly with the applicable capability. Further forecasting is useful when the choice depends on a missing or uncertain demand premise. Keep a protected-service or peak requirement explicit even when average consumption is lower.

EAM.4:4.2 - Construct an applicable observation basis

Choose the boundary at which demand will be compared with asset contribution. For a water district, distinguish water delivered to users from water entering the district: distribution losses make the quantities different. For a transport service, trips requested, passengers carried and vehicle movements likewise need a stated relation.

Recover present use, unmet requests and committed future use. Establish whether the observations cover the relevant users, place, period and operating conditions. Rationing, failure or inaccessible capacity can suppress recorded delivery. Obtain the missing need estimate or retain that uncertainty; relabeling observed delivery does not recover it.

Separate components whose drivers or possible interventions differ. Household use, other use and losses may be useful for a water decision. Reconcile their sum with the total on the same boundary and interval. If they disagree, investigate the mismatch that could affect the choice. A residual between compatible inlet and customer measurements may estimate losses; an unexplained discrepancy between incompatible meters cannot be assigned that meaning.

Keep the observation and its limitations available alongside the component account. More detailed segmentation is useful when it changes an option or the needed forecast. It is unnecessary merely to make the account larger.

EAM.4:4.3 - Vary drivers and form coherent scenarios

For each material change, explain how it affects a component: more users, different use per user, a new industrial commitment, changed losses or a shared environmental condition. Apply that change to the appropriate base. For example, a 10% increase in household use changes the household component, not automatically the district’s losses and industrial use.

Combine component values that can obtain together. Several site maxima can occur at different hours; weather can also make formerly separate peaks coincide. Where timing matters, construct a common-period profile or obtain the applicable specialist account. Preserve location, service class and quality conditions that a total could conceal.

Form an unchanged-policy baseline before crediting a proposed demand-management measure. Describe a measure’s affected users, expected effect, delivery conditions and cost as an alternative for EAM.7. Use its reduction only in the scenario where those conditions hold. A proposed service reduction remains subject to the relevant authority.

Test the drivers that can change eligibility or preference. A justified range or a few explicit scenarios can be sufficient. If an option has 100 units of spare contribution, an uncertain additional demand spanning 90–170 leaves its adequacy unresolved; a range wholly above 100 establishes that this option cannot cover that demand range without another contribution. This threshold can identify a useful further inquiry. Give a scenario a probability only when evidence supports that interpretation.

A more elaborate forecast is needed when an important dependency, changing population or response to price, weather or restrictions cannot be supported by the simple account. Ask the specialist for the demand at the required boundary and periods, the relevant driver combinations, uncertainty and limitations. The receiving asset decision still compares the returned result under those conditions.

EAM.4:4.4 - Return the demand and the premise that could change it

Compare the constructed demand with the contribution being considered, including losses, coincidence, storage and operating conditions through applicable relationships. Return quantity, recipients, location, period, drivers and uncertainty conditions to EAM.6 and EAM.7. Keep the source of an authorized commitment distinguishable from the evidence for a forecast.

Stop when the account distinguishes the useful options or identifies a specific unresolved premise. Obtain further forecasting or measurement when its attainable answer can change the choice or warranted claim enough to justify its burden and delay. When an observation changes a relied-on driver, EAM.13 returns to this account and the affected capability or alternative; unchanged components can remain usable.

EAM.4:5 - Archetypal Grounding

EAM.4:5.1 - Use a supplied requirement

In CityWater, North’s dry-window minimum is 700 m³/h and its wet-season minimum is 1,100. Current usable capability is 1,000. An annual average of 800 would not establish adequacy for the wet season: the explicit deficit is 100 m³/h at that required time. Both shortlisted C arrangements add 200 and pass this quantity comparison under their supplied qualifications.

Now suppose a new forecast suggests 1,250 in a later period. That forecast is not automatically a revised mandate. The practitioner reports that the current 1,200-capability option would fall short by 50 under this scenario and identifies which service or investment decision would use it. A sufficiently credible and consequential scenario can warrant another option without inventing a new commitment.

EAM.4:5.2 - Build the scenario from its components

In a separate constructed district, Westbank, compatible observations of an unrestricted critical hour give 1,000 m³/h at the inlet: 600 for households, 300 for other users and 100 losses. The case supplies compatible measurement coverage and the loss estimate. Proposed usable capability at the same inlet is 1,200 m³/h; required quality is unchanged.

The calculation is 600 × 1.10 + 300 + 140 = 1,100. It leaves 100 m³/h of contribution available within the proposed capability. A separately supported new industrial requirement of 150 during that same hour gives 1,250 and exceeds capability by 50. The industrial addition is counted once: it was absent from the 300 base.

If the industrial maximum occurs at another hour, the practitioner obtains the other components for that hour before forming its total. Adding unrelated maxima would not establish the actual peak. If the original 1,000 observation was rationed, the unrestricted baseline first needs an applicable estimate of suppressed use.

A proposed leakage measure may reduce the scenario’s losses from 140 to 80. With the industrial addition, the total would then be 660 + 300 + 150 + 80 = 1,190. EAM.7 can compare that measure with added supply, using its cost and evidence of achievable reduction. The ten-unit margin exists only while the assumed reduction, coincidence and other contributions remain supported. Treating the proposed 80 as the unchanged-policy loss estimate would hide the intervention that makes the option work.

These values illustrate the construction. They neither reconstruct CityWater’s supplied demand figures nor establish an empirical forecast for another district.

EAM.4:6 - Bias-Annotation

Observed delivery favors users who currently receive service. Consider excluded or suppressed demand when it changes the intended outcome. Demand reduction can move burden onto users whose interests are absent from the investment meeting.

EAM.4:7 - Conformance Checklist

Can the reader recover the observation base and each material driver? Do component sums share a boundary and period, with suppressed use and coincidence addressed where they matter? Are the unchanged-policy baseline and proposed measures distinct? Are commitments, observations and forecasts distinguishable? Does each selected scenario change a decision or claim, and is any probability supported?

EAM.4:8 - Common Anti-Patterns and How to Avoid Them

Comparing average demand with peak capacity can answer the wrong question. Compare required service at its actual window.

Using forecast demand as an authorized obligation silently changes the decision. Preserve the forecast’s evidence and let the relevant authority decide any commitment.

Crediting a proposed reduction in the baseline conceals the option needed to produce it. Keep its effect with its implementation conditions and burden.

EAM.4:9 - Consequences

Asset alternatives can be sized and timed against a need whose construction is recoverable. Some expansion proposals become unnecessary, while a local or seasonal deficit becomes explicit. Changing one driver can reopen the affected scenario without rebuilding adequate observations. The account remains qualified by its assumptions and does not guarantee future use.

EAM.4:10 - Architectural Rationale

Capacity is judged relative to a receiving service. EAM.4 supplies the demand construction and its conditions; EAM.6 determines what an asset arrangement can deliver, and EAM.7 compares ways to close the gap. Keeping forecasts, commitments and proposed measures distinct supports both a direct known-requirement comparison and adaptation when the demand basis changes.

EAM.4:11 - SoTA-Echoing

Choose the least burdensome supported comparison that distinguishes the asset options. C.16 supplies measurement and uncertainty distinctions; OPS.1 supplies the service and commitment account. North’s known 1,100 m³/h requirement already exposes a 100 m³/h shortfall. A more accurate annual average would not resolve that peak-service question.

The Environment Agency, Natural Resources Wales and Ofwat’s Water resources planning guideline, updated 16 June 2026, §§6.1 and 6.4.1–6.4.3, develops component demand, the observed baseline, critical periods and assumptions before additional measures. EAM adapts that contribution in the component reconciliation and driver construction above. The Westbank case shows why a changed driver or proposed reduction changes the asset comparison. Its values and arithmetic are constructed here.

A full specialist forecast is preferable when the relevant dependencies or uncertainty cannot be supported by that small construction. Request its result for the actual asset boundary and decision horizon. Reopen the method choice when new observations invalidate a driver or range, a changed period reveals a consequential peak, or the decision needs a fuller forecast. The water-planning source’s jurisdictional duties and planning horizon remain with that source.

EAM.4:12 - Relations

EAM.2 supplies the service contribution and its source. OPS.1 supplies operating commitments and populations. EAM.6 consumes the scenario’s quantity, place, period and conditions to compare capability; EAM.7 uses its gap and qualified demand-management possibilities to develop alternatives. EAM.13 returns changed observations or commitments to the affected part of this account.

EAM.4:End

EAM.5 - Assess Asset Condition and Performance

Type: Method Status: Stable

EAM.5:1 - Problem frame

Use this pattern when condition observations or service performance can change an asset decision. A warning appears on a dashboard while the asset continues delivering service, or apparently good availability conceals deterioration.

Start with the claim the decision needs. Return an applicable account of observed condition, its supported interpretation and the service consequence. Reuse an adequate maintenance or operating result instead of commissioning another assessment.

EAM.5:2 - Problem

Condition, delivered performance and future failure are different claims. A vibration increase can be real without identifying its cause or remaining life. Successful service during one interval can coexist with a condition that requires intervention. Aggregating them into a single health score can hide the reason an option is eligible or unacceptable.

EAM.5:3 - Forces

Earlier interpretation can improve response while false signals cause unnecessary work. More observations can clarify deterioration but impose access, analysis and delay costs. The useful resolution depends on the asset choice, duty, consequences and time available.

EAM.5:4 - Solution

Identify the asset, installed configuration, required functioning and decision horizon. Recover the condition account from MNT.4 when available. Check the measurement location, method, units, operating state, observation window and relevant limitations before comparing values.

Keep observed, inferred and forecast claims separate. State what changed in the observations, what the applicable diagnostic evidence supports and what future-duty assumptions a forecast requires. Use a specialist’s diagnosis where the mechanism matters; an alarm alone does not supply it.

Recover the relevant service-performance evidence. The useful content from OPS.18 might be an affected population, observed loss, quality result or reliability evidence, with its requirement and window. A favorable operating decision is not an asset-condition certificate.

Relate condition and performance to the proposed options. Identify what contribution is at risk, the consequence of delay and the supported intervention effect. Distinguish a condition ranking from risk: risk additionally depends on the exposure, uncertainty and consequence needed for this decision.

Reconcile apparent disagreements before drawing a stronger conclusion. A change in sensor, load or reporting population can explain a discontinuity. When no adequate correspondence exists, retain separate accounts and state the claim they cannot jointly support.

Return the supported interpretation and its implication for EAM.6 or EAM.8. Ask for more evidence only when its attainable result could change the option, response or justified claim enough to warrant the full burden. If the existing condition assessment answers the recipient’s question, provide it and finish the inquiry. Estimate remaining life only when that further answer is needed.

EAM.5:5 - Archetypal Grounding

In the constructed D case, the supplied maintenance account identifies abnormal increasing vibration under comparable duty. A separate specialist diagnosis and policy qualification support the initial intervention and five-year continued-use policy under stated conditions. Those are distinct premises; the vibration observation does not establish the policy by itself.

Suppose the operating record also shows delivery meeting the service requirement during the observed month. The practitioner can report both maintained service during that month and abnormal condition needing the supported response. Neither claim erases the other.

If later inspection finds a different structural defect outside the policy’s qualification, the EAM practitioner removes D continuation from the eligible alternatives. The portfolio changes to FFLR under the common application’s unchanged limits. A continued green service dashboard does not restore the invalid engineering support.

EAM.5:6 - Bias-Annotation

Easily measured signals can dominate attention while poorly observed failure mechanisms are neglected. Preserve the measurement’s actual coverage. A predictive model’s apparent precision can also disguise a duty change or insufficient evidence for its receiving use.

EAM.5:7 - Conformance Checklist

Do the records concern the same asset and duty? Are observation, diagnosis, forecast and service result distinguishable? Does the inferred consequence follow from applicable evidence, and is the option’s qualification still valid?

EAM.5:8 - Common Anti-Patterns and How to Avoid Them

Interpreting a health score as a remaining-life date gives an unsupported forecast. Recover the model and duty assumptions or report the narrower condition result.

Interpreting current service success as proof of sound condition ignores deterioration. Keep the actual condition and functioning claims separate.

EAM.5:9 - Consequences

The asset decision can use the available evidence without overstating it. Some options become conditional or ineligible; some investigations are unnecessary for the bounded answer. Remaining uncertainty is visible at the claim it limits.

EAM.5:10 - Architectural Rationale

The pattern joins condition and performance at their asset consequence while leaving diagnosis, measurement and operating decisions with their supplying practices. A single score is convenient only when its construction and intended use preserve the distinctions the choice needs.

EAM.5:11 - SoTA-Echoing

For deciding what the available condition evidence implies for an asset option, adopt MNT.4’s separation of observation, interpretation and forecast, and use the applicable service-evidence component of OPS.18. The Solution matches those claims to the actual unit and duty before using them in eligibility or consequence reasoning. In D’s case, the supplied diagnosis and policy qualification support the continued-use option while the observed vibration alone supports a narrower condition statement. Reusing those adequate results is the selected answer to the present question.

A serious technical alternative, when the asset choice needs a life forecast, is to fit a degradation model and project time to a supported failure criterion. The NIST/SEMATECH e-Handbook of Statistical Methods, section 8.4.2.3, “Fitting models using degradation data instead of failures”, supplies an established regression-based comparator and its physical, measurement and model assumptions. It is useful where that relationship and future-duty transfer are supported; a vibration trend by itself does not supply them. Adapt this modeling route when an obtainable life forecast could change the asset policy or timing. For the already qualified D alternatives, developing it anew would add data, fitting and validation work without being necessary for the stated comparison. The deliberate trade-off is a supported option implication with no independently derived remaining-life date. Neither the handbook nor MNT.4 supplies a real pump’s failure threshold. Reopen the choice when the diagnosis, duty or policy qualification changes, or when a forecast’s expected decision contribution justifies the work of establishing its applicable model and evidence.

EAM.5:12 - Relations

EAM.3 establishes the information match. MNT.4 supplies condition interpretation and MNT.6 diagnosis and intervention content. OPS.18 supplies the relevant operating evidence. EAM.6 assesses consequences and capability; EAM.8 uses the account in asset alternatives. A.10 and C.16 support the relied-on evidence and measurement claims.

EAM.5:End

EAM.6 - Assess Asset Capacity, Resilience, and Interdependence

Type: Method Status: Stable

EAM.6:1 - Problem frame

Use this pattern when an asset option must meet demand through a particular arrangement, outage or disruption. The total installed rating appears sufficient, but the needed contribution depends on shared assets, access, timing or recovery.

Begin with the service criterion and one applicable capacity bound. Return the supported capacity and consequence account, including the condition that makes a proposed option fail. A simple calculation can be sufficient. Develop the dependencies and recovery intervals when they determine what service remains available.

EAM.6:2 - Problem

Nominal ratings can be added even when the assets cannot supply the same service together. A fallback can rely on the same failed provider as the asset it is meant to replace. Normal-load adequacy and a successful isolated-outage calculation can then conceal loss of several contributions together.

Recovery also changes the answer over time. Enough stored reserve for one interval may be exhausted before another asset becomes usable. A single final recovery time hides that intermediate service failure.

EAM.6:3 - Forces

Reserve capability and recovery provisions cost resources while protecting a specified service. Pooling can improve utilization but create common dependencies. More elaborate models can improve a consequential assessment, but unsupported detail cannot establish a probabilistic reliability claim.

EAM.6:4 - Solution

EAM.6:4.1 - Establish the contribution being tested

Recover demand, required service, configuration and horizon. Keep quantities and time units compatible. EAM.4 can supply scenario demand and its place, period and driver conditions; EAM.5 can supply the applicable condition concern. Use OPS.10 or a specialist result to distinguish nominal capability from usable contribution.

State where the service must be delivered and which population or function it protects. An aggregate spare capacity elsewhere is useful only if the arrangement can deliver it where and when needed. Begin with a supply or load bound that the available inputs support.

EAM.6:4.2 - Derive the disturbance from actual dependencies

Identify the asset contributions and the dependencies that can change the answer. Follow shared power, control, providers, access, storage or another asset’s functioning to the service they enable. Explain which contributions cease, degrade or remain usable when a selected dependency is lost. Include a common dependency even when it crosses the portfolio’s ownership boundary.

Test a fallback against that same loss. A second pump on the failed feeder supplies no replacement flow until its needed power is restored. An alternative is independent of that feeder loss only when its power, control, connection and other necessary support remain usable under the stated scenario. This is a dependency claim for the named disturbance; a separate statistical independence claim needs its own evidence.

Choose adverse conditions because their consequences can change the asset decision: a named outage, common-provider loss or credible demand burst. Use an existing qualified scenario where it matches. Preserve simultaneous calls on shared reserve; one standby contribution cannot be allocated twice to incompatible users.

Compare material alternatives on the same disturbance and service criterion. An alternative may change the dependency itself, so recalculate the remaining contributions rather than carrying over the old consequence account.

EAM.6:4.3 - Follow service through recovery

Divide the disturbance into intervals at which demand, usable contribution or restoration changes. Use times to usable service, including the necessary access, work, testing and return conditions. A repair-completion estimate alone may omit the time before the contribution can actually be used.

For each interval, compare required service with supported available contribution. Where an additive bound is applicable, the positive difference is the deficit. Multiply a constant deficit by the interval length to obtain the reserve volume or resource needed during it. Carry the remaining usable reserve forward; test both its deliverable rate and its remaining amount. Account for other users’ simultaneous demands on it.

Credit replenishment only when its route, rate, timing and operating conditions are supported. If flows or demand vary materially within an interval, refine the intervals or obtain an appropriate time-dependent result. A total-volume comparison alone cannot establish pressure, quality or other delivery conditions.

The service requirement may include an allowed interruption, minimum contribution or restoration deadline. Apply that actual criterion to each interval. Report where and for how long it fails. Keep evidence for restoration timing separate from a proposed recovery plan: an unqualified time leaves the dependent conclusion conditional.

EAM.6:4.4 - Compare remedies and return the conditions

Compare additional capability, demand changes, sequencing, reserve, another fallback or changed recovery. Preserve burden and lost service moved to other users. An option that meets this scenario becomes a qualified candidate for the asset comparison, with its costs and remaining conditions.

Obtain a hydraulic, electrical, structural or stochastic result when that relationship determines the answer. Specify the arrangement, disturbance, required service and intervals it must address. A supported specialist result can replace an inadequate simple bound without restarting unrelated parts of the assessment.

Return the service envelope, failed scenario or precise missing result to EAM.7–EAM.10, and the relevant outage and recovery conditions to EAM.11. Stop when the receiving question is answered. Reopen on changed demand, dependencies, recovery support or operating conditions. Passing the selected scenarios supports only their stated scope.

EAM.6:5 - Archetypal Grounding

EAM.6:5.1 - A sufficient outage and buffer bound

CityWater’s North area has 1,000 m³/h usable capability before C is modified and needs 700 during the dry work window. Removing A’s 200 leaves 800; removing C’s 300 leaves 700. Each isolated outage passes the quantity bound. Removing both leaves 500, a 200 m³/h shortfall. Their individual feasibility therefore does not justify simultaneous work.

In an additional constructed variant, an independently qualified usable buffer contains 400 m³ and can cover that deficit at the required delivery conditions. The arithmetic gives 400 ÷ 200 = two hours. It cannot support a three-hour combined outage without another qualified contribution. This calculation assumes the stated usable volume and delivery rate; it does not derive them from tank size or establish water quality.

After the selected 200 m³/h addition, normal North capability is 1,200 against the wet minimum of 1,100. That comparison does not establish performance under every loss of station, power or control. Any such stronger claim needs its own applicable scenario or model.

EAM.6:5.2 - Shared failure and different recovery intervals

A separate constructed water system must continuously deliver 400 m³/h. Two units each supply a qualified 250 m³/h but share one feeder. An independent third source supplies 100 m³/h. Usable stored reserve is 300 m³, with delivery qualified for the deficits considered here. These are teaching inputs, not additional CityWater facts.

A feeder loss removes both 250 contributions. One returns after one hour and the other after two. During the first hour, only 100 m³/h remains, so preserving service requires (400 − 100) × 1 = 300 m³. The reserve is exhausted at one hour. During the next hour, 250 + 100 = 350 m³/h leaves another 50 m³/h deficit. The arrangement fails the continuous-service requirement despite normal capability of 600 m³/h.

Now consider a qualified additional 250 m³/h supply that can operate independently of this feeder loss and is usable after half an hour. Its support and connection are supplied as case premises.

Before the first feeder-dependent unit returns, required reserve is 150 + 25 = 175 m³. The initial 300 therefore covers the stated intervals, leaving 125 m³; no replenishment is assumed. From one hour, the available contributions meet the 400 requirement. The added supply is a feasible response to this constructed scenario, to be compared with other supported remedies and their burden.

If the added supply actually depends on the failed feeder, remove its contribution and the first conclusion returns: service fails after one hour. If it is independent but becomes usable only after 1.5 hours, the first hour exhausts storage and the next half-hour has a 50 m³/h deficit. Independence alone therefore does not establish timely service. Earlier availability, a further usable 25 m³ of reserve, a different restoration arrangement or another supported alternative could change that latter result.

Use actual dependency and restoration evidence before relying on such a calculation. The case establishes neither the probability of feeder loss nor the hydraulic feasibility of an unexamined network. EAM.7/.8 compare the supported remedy; EAM.11 must retain its half-hour availability and restoration conditions in the time arrangement.

EAM.6:6 - Bias-Annotation

Average service can hide a severe local loss. Inspect the protected population or location used by the decision. Dependency data can also overrepresent documented technical links while omitting access, providers or decisions that affect real recovery.

EAM.6:7 - Conformance Checklist

Are demand and usable capability compared under the same conditions? Can the reader trace the selected dependency loss to the contributions that cease? Does the reserve remain available under that loss and concurrent use? Are its amount and rate sufficient in every relevant interval? What supports restoration timing, and what stronger claim would require another model?

EAM.6:8 - Common Anti-Patterns and How to Avoid Them

Adding nameplate ratings can overstate joint capacity. Recover the actual combined service contribution.

Calling unused capacity “resilience” leaves the protected disturbance unknown. State the loss or demand scenario and test what remains deliverable.

Using final restored capacity to cover an earlier deficit hides interrupted service. Follow the contributions and remaining reserve through the intervening intervals.

EAM.6:9 - Consequences

The practitioner can reject an infeasible combination or identify a proportionate recovery change before committing resources. The account shows which dependency or restoration premise changes the result, so the affected alternative or timing can be reconsidered. It remains conditional on the modeled service, dependencies and evidence.

EAM.6:10 - Architectural Rationale

The same arrangement supplies normal service and responses to disturbance. Recovering its dependencies constructs the scenario; interval comparisons establish its service consequences. OPS.10 and specialist models supply applicable capacity reasoning, while EAM relates that result to asset choices and recovery conditions. A necessary bound and a sufficient supported scenario have different reach.

EAM.6:11 - SoTA-Echoing

For a named outage, first use OPS.10’s qualified capacity/service reasoning and an applicable supply or duration bound. The constructed 400 m³ buffer and 200 m³/h deficit establish a two-hour limit, sufficient to reject the three-hour proposal.

IAM Anatomy v4, §7.5.6, pp. 66–67, relates disturbance to the extent and duration of service loss and recovery objectives. GFMAM Landscape v3, §3.9, distinguishes asset and organizational resilience. The dependency and recovery construction above adapts those concerns to an asset choice: the shared feeder removes two contributions, and the time at which independent supply becomes usable changes the answer. More normal capacity alone does not resolve either fact.

For consequential water-network relationships, extended-period hydraulic analysis is a stronger alternative. The US EPA’s EPANET capabilities and hydraulic modeling description covers pressure, flow, tank levels and controls. Obtain such a result when deliverability or changing network behavior remains unqualified. Reuse an applicable existing result where available.

A supported simple bound is enough for the failed-duration question; dependency and interval reasoning is needed for the shared-loss question. Neither substitutes for an unresolved hydraulic relationship or failure-probability estimate. Reopen the choice of method when controls, demand, reserve delivery or restoration conditions change the answer beyond the current model’s reach.

EAM.6:12 - Relations

EAM.4 supplies demand and EAM.5 the condition concern. EAM.7/.8 use a required contribution or recovery alternative; EAM.9/.10 use the resulting service and dependency constraints. EAM.11 consumes the interval-specific outage and recovery conditions. OPS.10 supplies qualified capacity reasoning, and C.16 supports compatible quantities and uncertainty.

EAM.6:End