Pump Size Calculator Project Checklist

Introduction

Pump sizing involves a dozen small inputs, and forgetting any one of them is how systems end up wrong. This checklist compresses the entire sizing workflow — from the estimating guide, the formula guide, and the common mistakes guide — into a single verify-before-you-buy pass. Print it, work it top to bottom, and don’t spend money until every box is checked.

The arithmetic itself lives in the Pump Size Calculator — this page makes sure the numbers you feed it are complete and honest.

Open the Pump Size Calculator

Phase 1: Demand — How Much Water

☐ Listed every fixture/appliance the system serves (faucets, showers, toilets, laundry, hose bibs, irrigation zones).
☐ Assigned a realistic flow to each and identified the plausible simultaneous peak — not the total, not the average.
☐ Peak flow recorded: _____ GPM (_____ LPM).
☐ Irrigation sized per zone (zones run one at a time) and confirmed whether household + irrigation peaks can coincide.
☐ Well yield verified ≥ peak demand (well log or drawdown test). If yield is lower, the plan addresses it (storage, low-yield pumping) — the pump must never out-pump the well.

Phase 2: Head — How Hard the Pump Works

☐ Static head measured vertically from the pumping water level (drawdown level, not resting) to the system reference point: _____ ft (_____ m).
☐ Dry-season / lowest expected water level considered; static head uses the worst case.
☐ Total equivalent pipe length tallied: straight runs + drop pipe + fittings as equivalent lengths: _____ ft (_____ m).
☐ Pipe diameter and material recorded (inside diameter, C-factor); friction loss looked up or computed: _____ ft (_____ m).
☐ Sediment filter pressure drop included at the dirty rating, not clean.
☐ Pressure head set from the highest required system pressure (cut-out, not cut-in): _____ psi → _____ ft (_____ m).
☐ TDH = static + friction + pressure = _____ ft (_____ m). Sanity-checked: does each component’s share look plausible?

Phase 3: Power — The Calculation

☐ HP = (GPM × TDH ft) ÷ 3960 ÷ efficiency, with efficiency = _____ (default 0.60 unless the pump curve says otherwise).
☐ Metric cross-check: watts = (LPM ÷ 60) × TDH m × 9.81 ÷ efficiency → _____ W ≈ _____ HP. Both unit systems agree.
☐ Rounded up to the next standard pump size: _____ HP. (Rounding down is never acceptable.)
☐ Duty point (GPM @ TDH) plotted on the candidate pump’s published curve — falls on/near the curve, toward the middle, not at either extreme.
☐ Suction check: if a surface pump, suction lift ≤ ~25 ft (7.6 m). If deeper, pump type is submersible or deep-well jet — confirmed.

Phase 4: The System Around the Pump

☐ Pressure tank: drawdown ≥ ~1 minute of pump flow; precharge planned at 2 psi below cut-in; bladder type.
☐ Wire: gauge sized for <5% voltage drop over the actual run length; submersible-rated cable for down-well; splices planned with heat-shrink kits.
☐ Pipe: diameter checked against velocity limits (~5 ft/s suction, ~8 ft/s discharge); upsized one nominal size if friction was marginal.
☐ Check valve(s): one at/near the pump confirmed; foot valve + strainer if surface suction.
☐ Isolation valves (full-bore ball type) planned for service; pressure relief considered where dead-heading is possible.
☐ Dry-run / low-water protection included (cutoff switch or pump protector), especially if well yield is uncertain.
☐ Surge protection planned (lightning is a leading pump killer).
☐ Water conditions addressed: sand (separator, intake placement), iron/pH/chlorides (materials selected accordingly).

Phase 5: Compliance and Paperwork

☐ AHJ contacted: permit requirements, licensed-contractor rules, and inspection scheduling confirmed (code compliance guide).
☐ Backflow requirements checked for the configuration (irrigation tie-in, booster on city water).
☐ Electrical: dedicated circuit, disconnect location, grounding, and any GFCI requirements confirmed with the inspector or electrician.
☐ Quotes (if pro): itemized against the same duty point — pump model/HP, wire gauge/footage, pipe type/footage, tank size, labor, warranty.
☐ Post-work plan: inspection, well disinfection + water testing before drinking, paperwork filed.

Phase 6: Documentation (Do It Now, Thank Yourself Later)

☐ Recorded: well depth, pumping water level and yield, pump make/model/HP, setting depth, wire gauge and length, pipe size and length, tank size and precharge, pressure switch settings, install date.
☐ Copy taped inside the control box / left with the system paperwork.
☐ Old pump’s spec sheet kept (if replacement) — “same as what’s in there” only works if it’s written down.

Red Flags — Stop and Revisit

If any of these are true, don’t proceed until resolved:

TDH was computed without friction loss. Go back to Phase 2.
Static head uses the resting water level. Get the pumping level.
Efficiency assumed above 70% on a small pump without a curve to prove it. Reset to 60%.
Surface pump with suction lift over 25 ft. Change the pump type, not the HP.
No pressure tank (or a waterlogged one being kept). Add/replace it.
Well yield unknown or below peak demand with no mitigation plan. Resolve before sizing.
Duty point off the pump curve entirely. Different pump, not wishful thinking.

Each of these is detailed with fixes in the common mistakes guide; the decision logic for who should do the work is in DIY vs. pro.

Related Guides

Estimating Guide — the measuring procedure behind Phases 1–2.
Pump Size Formula Explained — the math behind Phase 3.
Pump Size Complete Guide — the full sizing workflow in one place.
Material Guide — selecting everything in Phase 4.
Cost Guide — budgeting the verified spec.
Pump Size FAQ — quick answers to last-minute questions.

Frequently Asked Questions

Can I skip the metric cross-check if I work in imperial?

You can, but don’t — it takes thirty seconds and catches unit-mixing errors that otherwise surface as a wrong pump. Two unit systems agreeing is the cheapest verification in pump sizing.

What if I can’t find my well log?

Check with your local health department or well program — they often keep copies. Failing that, a well contractor can measure the static level with a sounder and run a drawdown test for the pumping level. Don’t guess the pumping level; it’s a primary input.

How do I check a pump curve if I’m buying online?

Manufacturer websites publish curves as PDFs for every pump model — search the model number plus “performance curve.” If a listing has no curve available, treat that as a red flag about the seller, not a reason to skip the check.

Should the checklist change for irrigation-only systems?

The structure is identical; only the inputs shift: flow becomes the zone design flow, pressure head becomes the sprinkler operating pressure plus elevation, and the tank is usually unnecessary (constant demand while running). Friction still matters — often more, since irrigation runs are long.

Who signs off that the checklist is complete?

You do, for a DIY job — honestly. For pro work, walk through it with the contractor before authorizing the purchase; an itemized quote mapped to these phases is the sign of a contractor who sized the system rather than guessing.

Get Your Number

A checklist only works if you actually work it — top to bottom, no skipped phases, no “close enough” on the red flags. When every box is checked, run the final numbers through the Pump Size Calculator one last time, confirm the duty point on the pump curve, and buy with confidence. The most reliable pump systems aren’t the ones with the best pumps — they’re the ones where nothing was forgotten.

Disclaimer: This checklist is a planning aid, not a substitute for professional design or code compliance. Site conditions, well yield, water quality, and local regulations vary — verify measurements on site, confirm requirements with your local authority, and consult a licensed well contractor or pump professional where needed.