Sump pumps · overview
Sump pump basics: what homeowners should know
A sump system moves groundwater away from your foundation before it becomes a basement flood. Knowing the parts, how primary and backup pumps differ, and why lift matters helps you maintain the system and know when to call a pro.
What a sump system does
Typical pieces:
- Basin (sump pit) — collects water from drain tile or a high water table.
- Primary pump — usually electric, turns on when the float (or electronic switch) rises.
- Discharge line — carries water outdoors or to an approved drain path, away from the foundation.
- Check valve — stops discharge water from flowing back into the pit when the pump stops.
The goal is simple: keep the water table under the slab from rising into living space. Landscaping grade, gutters, and downspouts still matter — a pump cannot fix every exterior drainage problem.
Primary vs backup
- Primary — handles normal inflow on household power.
- Backup — runs when the primary fails, the float sticks, or the power goes out (storms often bring both heavy water and outages).
Common backup styles (high level):
- Battery backup — second pump (or dual system) powered by a charged battery bank / inverter-style package. Needs battery maintenance and periodic testing.
- Water-powered backup — uses municipal water pressure through a venturi-style ejector when the pit rises. Needs adequate city-water pressure and flow; not available the same way on many private wells.
Many homes use primary + battery backup. Choose what matches your water source, outage risk, and how critical a dry basement is for you.
Horsepower, GPM, and head (lift)
Horsepower on the box is marketing shorthand. What matters is how many gallons per minute the pump moves at the height (head) you actually lift — vertical rise plus friction in the discharge pipe and fittings.
- A pump that looks strong at zero lift can be weak once you push water up a tall basement wall and out across the yard.
- Match published GPM-at-head charts to your lift, not a bigger HP sticker alone.
- Long or undersized discharge hose adds friction — another silent tax on capacity.
Check valves, freeze risk, GFCI, and alarms
- Check valve — without one, water falls back into the pit and the pump short-cycles or fights itself. A quiet 1½″ check valve is a common residential size — confirm yours.
- Discharge freeze — outdoor discharge that traps water can freeze shut in winter. Slope, freeze-protection details, and where the line ends matter; ice-blocked discharge is a common flood cause.
- GFCI / electrical — sump circuits should be installed to local code. Nuisance trips leave you unprotected — know where the outlet and breaker are.
- Alarms — high-water alarms (often battery-backed) warn you before water reaches the slab. Useful even with a backup pump.
- Battery backup — packages such as the Basement Watchdog BWSP cover primary failure or power loss; pair with a high-water alarm so you hear trouble early.
Maintenance and testing
- Pour water into the pit (or lift the float carefully per your manual) to confirm the primary starts and discharges outdoors.
- Test backup systems on their schedule — especially before rainy seasons and after storms.
- Clear debris from the basin; check that the float moves freely.
- Listen for short-cycling (rapid on/off) — often a check-valve, air-lock, or switch issue worth diagnosing early.
When to call a plumber or waterproofing pro
- Repeated flooding, cracked or undersized basin, or discharge that cannot be routed safely
- Electrical work you are not qualified to do; burned motors; failed floats
- Structural seepage, wall cracks, or drain-tile problems — often a basement waterproofing specialist rather than “just a bigger pump”
For install, electrical, or code questions, talk to a licensed plumber. For chronic seepage or foundation drainage, a basement waterproofing professional may be the better fit. For general residential water-system questions, you can also contact R.E. Merrill & Associates.