Well pump size by depth

How much pump a house needs depends on two things: the flow its bathrooms call for at peak, and how far the pump has to lift and push. This table reads the smallest Goulds 10GS model that meets each household demand at each pumping level, on a 40/60 switch.

Minimum pump flow to meet a seven-minute household peak without a supplemental supply, by bathrooms (Goulds).

Pumping level	1 bath (7 gpm)	1½ bath (10 gpm)	2–2½ bath (14 gpm)	3–4 bath (17 gpm)
60 ft	½ hp	½ hp	½ hp	½ hp
100 ft	¾ hp	¾ hp	¾ hp	¾ hp
140 ft	¾ hp	¾ hp	¾ hp	¾ hp
180 ft	¾ hp	¾ hp	¾ hp	¾ hp
220 ft	1 hp	1 hp	1 hp	1 hp
260 ft	1½ hp	1½ hp	1½ hp	1½ hp
300 ft	1½ hp	1½ hp	1½ hp	1½ hp
380 ft	1½ hp	1½ hp	1½ hp	1½ hp

— means no model in the 10GS series (½ to 3 hp, recommended 3 to 16 gpm) meets that flow at that depth on 40/60; a higher-flow series is needed. Flow needs above 16 gpm sit outside the 10GS recommended range.

How to use it

Start with the pumping water level from your well log or a pump test, add the height from the wellhead to the pressure tank and the pipe friction for your run, and read the row at or below that total. The calculator does the arithmetic and draws the head. The total dynamic head guide explains each part.

The 10GS series at a glance

Each motor size covers a band of depths. The chart lists a rating only where the pump is in its recommended range, so a bigger motor is not simply "more pump" at every depth — the larger models are not rated at shallow depths at all.

Model	HP	Rated at 40 psi	Rated at 60 psi
10GS05R	½	20–60 ft	—
10GS05	½	20–120 ft	20–60 ft
10GS07	¾	40–200 ft	20–160 ft
10GS10	1	60–280 ft	20–220 ft
10GS15	1½	140–420 ft	100–380 ft
10GS20	2	200–540 ft	140–500 ft
10GS30	3	280–740 ft	220–700 ft

Ratings: Goulds Water Technology, Model GS 5–25 GPM technical brochure B5-25GS (March 2012) — copy hosted by a retailer; the current Xylem brochure has no ratings tables.

Pumping level, not static level

The depth to read is where the water stands while the pump runs. A driller's log usually records both the static level and the level during a yield test; the second is the one to use. If only the static level is known, a pump test is cheaper than a pump that cannot keep up.