Sump Pump Installation & Repair

Where sump pumps actually matter in Los Angeles

Most of Los Angeles is slab-on-grade with no basement, so a lot of homeowners assume sump pumps are a Midwest problem. Then the winter storms arrive. The atmospheric river in February 2024 dropped a record 4.10 inches of rain on downtown LA in a single day, and the Christmas-week storm in December 2025 put parts of the LA Basin under a rare high-risk excessive rainfall outlook. When months of rain lands in a day or two, any space that sits below the surrounding grade becomes the low point the water finds.

In practice, that means hillside homes in the Valley and the canyons with rooms or garages cut into the slope, older homes with below-grade garages and driveways that pitch down toward the door, basement and cellar spaces in pre-war houses, lightwells and window wells, crawl spaces on cut lots where the uphill side sheds water under the house, and elevator pits and subterranean parking in small multi-unit buildings. A sump system in these spaces is simple: a pit at the low point collects the water, a pump lifts it up and out, and a discharge line carries it away from the foundation before it can pond against the structure or rise into the living space.

The other half of this work is not storm-related at all. Below-grade bathrooms and laundry rooms sit beneath the sewer line, so their drains cannot flow out by gravity. Those need a sewage ejector pump, a sealed pit-and-pump system that grinds and lifts wastewater up to the main line. It is a different machine than a groundwater sump pump, and we install and repair both.

Signs your pump needs repair or replacement

The worst way to find out a sump pump is dead is during the first big storm of the season, because that is the one day you cannot wait for a repair. The reliable test takes five minutes on a dry day: pour a few gallons of water into the pit and watch. The float should rise, the pump should kick on, the water level should drop quickly, and the pump should shut off without chattering. If any part of that sequence fails, the system needs attention before the rain does.

Between tests, the tells are audible. A pump that runs constantly even when the pit is nearly dry usually has a stuck or failed float switch, or it is fighting water that falls straight back down the discharge pipe because the check valve has failed. A pump that rapidly clicks on and off is short-cycling, which cooks the motor and switch. Grinding or rattling points to a damaged impeller or debris in the pit. Visible rust, a pump that trips the breaker, or a unit roughly 7 to 10 years old are all reasons to price a replacement rather than nurse it along.

One honest note: a sump pump is the remedy for water that reaches a below-grade space, not a substitute for fixing where the water comes from. If your garage floods because a surface drain is packed with mud, or water is ponding against the foundation because a downspout dumps beside it, we will tell you that, because a pump that runs less lasts longer, and sometimes drainage correction is the cheaper fix.

How we size and install it

Sizing is where sump installs go wrong, in both directions. A pump's advertised gallons-per-hour rating is measured at zero lift, and output falls hard with head height, the vertical distance the water must climb before gravity takes over. A 1/3 HP pump that moves well over 2,000 gallons per hour on the box can lose 30 to 40 percent of that at a 10-foot rise, which is a realistic lift out of a below-grade garage on a hillside lot. We measure the actual lift, the pipe run, and how fast water enters the pit during a storm, then match the pump curve to the job. Most homes land on a quality 1/3 or 1/2 HP submersible; a badly oversized pump is not extra safety, it short-cycles and wears out its switch early.

The install itself covers the details that determine whether the system works in year five, not just on day one: a properly set pit with a lid, a check valve close to the pump so the discharge column cannot drain back and re-trigger it, a union or disconnect so the pump can be pulled for service, and a discharge line routed to a legitimate drainage path away from the foundation. Storm and groundwater does not belong in the sanitary sewer, and hillside lots in particular have rules about where pumped water may go, so we route discharge to an approved point rather than wherever is convenient.

For any space where flooding would do real damage, we recommend a battery backup pump, and this is not an upsell. The storms that fill sump pits in LA are the same storms that take down power lines, so the primary pump is most likely to lose electricity at the exact moment it is needed. A battery backup unit sits in the same pit and takes over automatically, typically buying hours of intermittent pumping through an outage. We install and test the full changeover, not just the hardware.

Pricing and what moves it

Replacing a pump in an existing pit is the simplest job: in the Los Angeles area it typically runs $650-$1,500 installed depending on the pump quality and whether the check valve and discharge fittings should be renewed at the same time. A new sump system built from scratch, which means saw-cutting concrete, excavating and setting the pit, installing the pump, and running the discharge line, typically runs $2,500-$6,000. The spread is mostly about concrete, access, and how far the discharge has to travel to reach an approved drainage point. Adding a battery backup system typically runs $900-$2,200 installed depending on capacity. Sewage ejector pump replacement usually falls in the $1,200-$3,000 range because of the sealed pit and vent connections involved.

Every job starts with a free estimate and a written flat-rate quote before any work begins, so the price you approve is the price you pay. Last Drop Plumbing & Rooter is family-owned and based in Reseda, licensed as a C-36 plumbing contractor (CSLB #1120613), bonded, and insured. If a pump has died mid-storm and water is rising, we run 24/7 live dispatch at 818-292-3330, with a typical 30-90 minute response window in the San Fernando Valley.