Pits, floats, and spring melt
Sump Pump Repair Denver
Float, Discharge Freeze & Battery Backup Service
Most sump pumps in this corridor sit still for nine months a year, then get asked to save a finished basement during one wet week in spring. A machine that never runs is a machine nobody has tested. Yours deserves a bucket of water.
- Test it with a bucket
- Stuck floats and dead impellers
- Frozen discharge in January
- Battery versus water-powered backup
A pump that never runs is not a pump that works
Basements in the metro stay dry most of the year, and that's the trap. The pump sits in a few inches of still water from June through February while silt settles on the impeller, the float drifts against the basin wall, and the check valve flap dries stiff. Then a warm afternoon lands on a foot of wet March snow, the drain tile starts feeding the pit faster than it has in a year, and the pump sits its annual exam without studying. Test it quarterly instead. Pour five gallons in slowly, watch the float rise, listen for the motor, and confirm water actually leaves the house.
Know which pit you have, because it changes everything. A sump collects clean groundwater from drain tile around the footing and pushes it outside. A sewage ejector, common where a basement bath or laundry sits below the sewer line in newer builds around Thornton, handles waste and has a sealed lid with a vent pipe. If your pit smells like sewage or the lid is bolted down, treat a failure there as a contamination event: stop using every basement fixture, keep kids and pets out of the room, and don't handle standing water without gloves and boots. That's a call to make now, not Monday, and our sewer line guidance explains what tends to be behind it.
One rule before you climb down there for any reason. Water on a basement floor with a plugged-in pump, a freezer, and outlets at the baseboard is an electrical hazard first and a plumbing problem second. Kill those circuits at the panel while you're standing on dry ground. If the panel itself is in the wet area, you're done improvising: stay out and call an electrician or the utility.
What actually fails, in rough order
Float switches lead the field by a wide margin. Tethered floats hang up on the discharge pipe or the wall of a crock that was always a little too narrow. Vertical floats bind on their rod once silt works into the collar. Either way the pit fills while the pump does nothing, or the pump runs on and on because the float never drops back. Lift the float by hand: if the motor kicks on instantly, the pump is fine and the switch isn't.
Next comes the pump that runs beautifully and moves no water. That's a clogged impeller, usually silt, pea gravel, or drywall dust in a house under five years old, or it's a check valve that quit. A failed check valve announces itself: the column of water in the discharge pipe drops back into the pit a second after shutoff with an audible gulp, the pit refills itself, and the pump short-cycles all night until the motor gives out from the exercise.
After that the list gets shorter. An airlock at the pump body when the weep hole is missing or plugged. A GFCI outlet that tripped in November and got noticed in April. A piggyback switch plug that vibrated loose. And plain age, because pumps are consumable parts, not fixtures, and one that's been in the pit for a decade owes you nothing.
- If the motor hums but nothing spinsthe impeller is jammed or the capacitor is done. Unplug it before you touch anything.
- If it cycles every couple of minutes with no rainsuspect the check valve or a discharge line dumping too close to the foundation.
- If the pit is full and the pump is silentcheck the GFCI and the float before you shop for a new pump.
- If the pit smells like sewagethat's an ejector, not a sump. Stop using basement fixtures and get help today.
Repair it, replace it, or add a second line of defense
The repair math is simpler here than in most plumbing. A check valve, a float switch, or a discharge fitting is an inexpensive part and a short visit. A tired pump with a chewed impeller and eight winters on it is worth replacing outright, because the labor to pull it and set it is nearly identical either way and you'd rather spend that trip on new equipment.
Along the Front Range, a straightforward pump swap with a standard third-horsepower cast iron or thermoplastic unit commonly lands in the mid hundreds installed, more if the discharge plumbing gets rebuilt first. A battery backup system with a deep-cycle battery, its own pump, and a charger adds several hundred to well over a thousand, depending on how much runtime you want. Water-powered backups sit in a similar band and need decent municipal pressure to work at all, which rules them out on well systems entirely.
The backup decision isn't really a plumbing decision. It's a question about what's downstairs. An unfinished storage basement with a floor drain can take an inch of water and a wet vacuum. A finished basement with carpet, drywall, and a home office cannot, and the failure that matters here is a heavy spring snow that loads the water table and drops power lines in the same afternoon. Your pump is on a circuit. When that circuit goes, the groundwater does not stop arriving.
| Setup | What it handles | What still sinks it |
|---|---|---|
| Primary pump alone | Normal groundwater and an ordinary wet week | Any outage, and its own failure |
| Primary plus battery backup | Outages lasting hours, and a dead primary | A battery nobody tested in three years |
| Primary plus water-powered backup | Outages of any length, no charging needed | Weak city pressure, and wells entirely |
| Two primaries, separate circuits | One pump dying in the middle of a storm | An outage that takes out both circuits |
Need this handled this week?
Start a quoteWhere the water goes after the pump
The discharge line fails more often than the pump and gets a fraction of the attention. Where it exits the wall and runs across the yard, it can freeze solid during a cold snap, and a pump firing into a closed pipe either overheats or simply moves nothing while the pit rises. The usual fixes are unglamorous: a larger diameter on the exposed run, a steady downward slope so nothing sits in the line, and a relief opening near the exit so the pump can dump somewhere if the far end ices up.
Termination matters just as much. A line that ends five feet from the foundation is a circle, not a discharge, feeding the same drain tile that feeds the pit, which is how a pump ends up running every three minutes in a dry month. Get it downgrade and well away from the wall, and keep it out of the sanitary sewer.
The hardest week of the year is a melt week, when a foot of heavy wet snow meets a 55-degree afternoon and turns into groundwater in two days. Towns that remember what water can do, Longmont and the St. Vrain corridor among them, tend to have homeowners who check their pits in February. That's the right instinct. Pull the lid, clear the silt, lift the float, pour a bucket, and walk outside to watch the discharge run.
Related work
More emergency services
Burst Pipe Repair
split copper and PEX, shutoff sequence, temporary containment, permanent fix
→Water Main & Service Line Repair
the buried service line from meter to house, leaks in the yard, replacement
→Slab Leak Detection
warm spots, unexplained bills, acoustic and thermal location, reroute vs. break-in
→Bathroom Leak Repair
ceiling stains below baths, shower pan failures, supply and drain leaks
→Gas Line Repair
smell-gas protocol, appliance lines, sediment traps, when to evacuate first
→Where we cover
Front Range cities we write for
Questions we actually get
Sump Pump Repair: quick answers
How often should a sump pump actually run?
It depends entirely on your lot and the season, and the pattern matters more than the count. A pump that cycles during spring melt and after heavy rain is behaving normally. A pump that runs every few minutes in a dry July is being fed by its own discharge, a failed check valve, or groundwater from a leak somewhere, and each of those has a different fix.
Can I replace a sump pump myself?
Many homeowners can. It's an unplug, a union fitting, and a lift. The parts people get wrong are the check valve orientation, the weep hole that prevents airlock, and a float with enough clearance to swing without touching the wall. If the pit holds sewage rather than groundwater, skip the project entirely and hire it out.
Is a battery backup worth it if we rarely lose power?
The question isn't how often power fails, it's whether power and water arrive together. Around here they do: heavy wet spring snow loads branches onto lines while it soaks into the ground. If the basement is finished, a backup costs a fraction of one flood. If it's bare concrete with a floor drain, it's a reasonable thing to skip.
Pit filling faster than it empties?
Tell us what the pump is doing and what's downstairs, and we'll route it right.
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