Cost to Fill a Pool Calculator

How much does it cost to fill a pool with water?

From a city supply, less than most people fear: a typical residential pool holds 10,000–20,000 gallons, and city water runs a few dollars per thousand. The arithmetic is gallons ÷ 1,000 × your rate. What moves the answer by 2× is whether your utility also bills sewer on those gallons — most do, by default — and the water truck is a different price class altogether. At mid-range US rates:

Water $5 and sewer $6 per 1,000 gal — mid-range for US cities; tanker $300 per 6,000-gal load, rounded up to whole loads. Metro rates run from under $3 to over $12 per 1,000 gal, so use yours in the tool. A 15,000-gal fill is about 1.6 months of an ordinary household's water use, which is why it shows up on the bill.

What's my water rate? Reading the bill

Utilities price water in one of three units, and the number you want is the volume charge, not the fixed service fee. Per 1,000 gallons is the easy one. Per CCF or HCF — a hundred cubic feet, sometimes written "100 cu ft" or just "units" — is 748 gallons, so a $5 CCF is $6.68 per 1,000 gal; the tool converts either way. Outside the US it's per cubic meter, 264 gallons. Two things to check on the bill: whether the rate is tiered — most cities charge more per unit above a monthly threshold, and a pool fill goes straight into the top tier, so use that price — and whether there's a separate line for sewer, wastewater or sanitation billed per unit of water. That line is the subject of the next section, because it's often the bigger one.

Do you pay sewer charges on pool water?

Usually, unless you do something about it. Sewer isn't metered — nobody measures what leaves your house — so most utilities bill it on the water that came in, on the assumption that it all went down a drain. Pool water doesn't, but the meter can't tell. And the sewer rate is frequently the larger of the two: treating water costs more than supplying it. Three mechanisms take it off a fill, and every ranking page mentions the first and stops:

• A pool-fill credit. Many utilities — JEA in Jacksonville, Miami-Dade, Fond du Lac, Palm Coast and hundreds of smaller ones — will remove the sewer charge on a fill if you ask. Typical conditions: once a year (sometimes every two or five), a request within 30–60 days of the fill, meter readings or a photo before and after, an account in good standing, and often an affidavit. Search your utility's name plus "pool fill adjustment" before you fill, so you take the readings.
• A deduct meter. A second meter on the outdoor line — irrigation and pool — whose gallons are subtracted from the sewer calculation every month, forever. Installing one costs a few hundred dollars plus a plumber, which pays back in a couple of seasons for a pool that's topped off through a dry summer.
• Winter averaging. Common across Texas, the Southeast and much of the Southwest: sewer volume is set from your average use in the winter months, when nobody irrigates, and that average is applied for the following year. A fill in summer is billed no sewer at all. A fill in winter is the trap:

Winter averaging with a 3-month window (Dec–Feb is common; Nov–Feb makes it 3× instead of 4×) and sewer at $6 per 1,000 gal. Some utilities cap the averaged volume or let you request an adjustment for a known fill — ask. Water at $5.

Garden hose or water truck?

A hose is a tenth of the price and takes a day or two; a truck is done in an hour or three. How long the hose takes is the number most pages guess at ("24–48 hours"), and it depends on one thing: what your spigot actually delivers. Hose flow charts say 15–25 gallons a minute for a ⅝-inch hose at 50 psi, but that's a short hose with the end wide open on a full-pressure line. A real house — a long run, 40–60 psi at the meter, someone showering — delivers 5–12. Time a 5-gallon bucket: 40 seconds is 7.5 GPM. Then read your row:

Hours of continuous flow at the stated gallons per minute. Two hoses from two spigots help only if the house supply can feed both — often it's the same 12 GPM split two ways. A water truck delivers a 6,000-gal load in 30–60 minutes.

The truck earns its price in three situations: you're on a well that can't sustain a day of pumping (below); the pool has to be swimmable by the weekend and it's Friday; or there's no city water at the property. Some buyers also order a truck for a new plaster pool because the finish should be filled without stopping — a hose does that fine as long as nobody turns it off overnight. A few cities let you buy from a fire hydrant through a permit and a rented meter, which is the fast-fill option at city-water prices where it exists — worth one phone call if you have a long fill ahead.

Filling from a well

The water is free; the risk isn't. The electricity is trivial — 42 hours of a 1,000 W pump at 6 GPM for 15,000 gallons is about $7.08 at $0.17/kWh; the tool's well mode prices yours. What matters is the well's recovery rate, the gallons a minute the aquifer refills it at, which is often below what the pump can draw. Pull it down faster than that for hours and the pump runs dry, cavitates and can burn out — a four-figure repair on a free fill. Fill in sessions with rests, or throttle the flow to the recovery rate if you know it, and expect well water to bring iron, manganese or hardness with it: test the fill water before it's in the pool, because a sequestrant is a lot easier to plan for than a brown pool is to fix.

How much does a partial drain cost?

This is where the calculator earns its keep, because the drains that matter — for high stabilizer, calcium or salt — are decided on water cost, and the water cost is smaller than the dread. A third to a half of the pool, priced two ways:

Water + sewer at $11 per 1,000 gal; the second line is water only, which is what you pay with a pool-fill credit or outside a winter-averaging window. The dilution calculator turns your readings into the percentage — and shows why anything over 40% is safer as two stages.

When is draining cheaper than chemicals?

For stabilizer and salt, always, because there's no chemical route down: nothing you can add removes CYA or salt, and the "CYA reducer" products sold for the purpose cost $100–150 a treatment and work unreliably. The comparison that actually matters is the cost of living with high CYA. The chlorine level a pool needs scales with its stabilizer, so every dose scales with it too — a SLAM most of all. On a 15,000-gallon pool, the shock level at CYA 100 is 40 ppm against 20 at CYA 50, so just reaching it takes 4.8 gallons of 12.5% liquid chlorine ($29) instead of 2.4 ($14.40) — and you hold that level for days, so the real gap is several times that. The 50% drain that takes CYA from 100 to 50 costs $83 with sewer, $38 without, and since 50 is the target you don't buy stabilizer afterward. One algae episode pays for it.

For calcium hardness the chemical alternative is real but permanent: a sequestrant keeps calcium in solution at a few dollars a month, indefinitely, while a drain resets the number for the price above. In a hard-water area where the fill water itself is 300 ppm, neither wins outright — the saturation index decides whether the calcium is a problem at all. For pH, alkalinity and chlorine, never drain: the chemical fix costs a few dollars and the water doesn't need changing.

What a fresh fill needs before it's a pool

The honest surprise of a full refill is that the water is the cheap line. Tap water arrives with no stabilizer, no salt, no chlorine and often little calcium, and putting those in costs about as much as the 15,000 gallons did — more, on a salt pool or once a sewer credit has taken the water bill down to $75:

Doses from the same engine as the dosing calculators; retail assumed at $4/lb stabilizer, $0.25/lb salt (a $10 bag), $2.5/lb calcium chloride. A chlorine pool with hard fill water skips the salt and the calcium; a salt pool on plaster with soft water needs all three — $89 to $189 against $165 of water. Chlorine to hold the new water is on top, and it's daily.

Which is the case against a casual full drain: partial drains do the same chemistry job for a fraction of the water and keep half the chemicals you already bought. When you do refill, test the fill water first, then rebuild in order — chlorine immediately, because a fresh pool is unprotected, then pH and alkalinity, then stabilizer and salt. The dashboard turns the first test into every dose at once.

What does a pool cost in water over a season?

Less than the fill, more than nothing. An uncovered 450 ft² pool in ordinary summer weather evaporates about 85 gallons a day — 12,780 over a five-month season — and a sand or DE filter backwashed every couple of weeks sends another 2,679 or so down the drain. Call it 15,459 gallons of top-off, $170 at $11 all-in: about 1.0× the pool's volume replaced every year without ever opening the drain, which is also why calcium and CYA creep upward in dry climates. A cover stops most of the evaporation half — the cover savings calculator prices it for your weather — and the sewer rules above apply to top-offs too: on a winter-averaged bill, summer top-off water carries no sewer charge at all.