Overview
A sump pump sits in a pit at the lowest point of a basement or crawl space and pumps away groundwater that collects there, usually through a discharge line that exits the house. When it works, most people forget it exists. When it fails during heavy rain or snowmelt, water can rise into finished basements quickly, which is why sump pump problems are often treated as urgent.
Pumps fail for predictable reasons: a stuck or tangled float switch, a motor that has worn out, debris clogging the intake, a frozen or blocked discharge line, a check valve that has failed, or a power outage. Some homes also have pumps that run constantly because the pit fills faster than expected, which may indicate a high water table, a drainage issue outside, or a pump that is undersized.
Backup options exist for homes where a failure would be costly. Battery backup pumps can run during a power outage for a limited time, and some homes use water-powered backup pumps where municipal water pressure allows. High-water alarms are an inexpensive way to get an early warning before water reaches the floor.
What the work usually involves
- Testing the pump by filling the pit and watching the float and pump cycle.
- Inspecting the float switch, check valve, discharge line and electrical connection.
- Clearing debris from the pit and intake screen.
- Replacing the pump with a properly sized unit if the motor has failed.
- Discussing backup pumps, alarms and discharge routing.
- Checking where the discharge empties, since water should be directed away from the foundation.
What affects the outcome
- Local rules may restrict where sump water can be discharged, such as into the sanitary sewer.
- Battery backups have finite run time and the batteries need periodic replacement.
- Testing a pump a few times a year, especially before wet seasons, can catch problems early.
- A pump that runs constantly will wear out faster and may signal a drainage issue worth investigating.
- Pedestal and submersible pumps differ in noise, lifespan and how much space they need.
- Discharge lines can freeze in cold weather. Routing and slope matter in climates with hard winters.
Before you send an inquiry
- Describe any water damage to floors, ceilings or walls, since that can affect both the repair and any insurance claim.
- List the times you can be reached and whether someone will be home to provide access.
- Mention the approximate age of the home and whether you know what type of piping it has, such as copper, PEX, galvanized steel or cast iron.
- Say whether you own or rent. Renters usually need to involve the landlord or property manager before work begins.
- If you have had related work done recently, note the date and what was done.
Warning signs
- Prices that change significantly after arrival without a clear explanation of what was discovered.
- No clear answer about warranties on parts and labor.
- Pressure to decide immediately on a large replacement without a clear explanation of why a repair will not work.
- Requests for large cash payments up front before any work or materials are scheduled.
- Unwillingness to provide license or insurance information when asked.
Questions to ask a provider
- Where should the discharge line empty, and is my current setup acceptable?
- Can you add a high-water alarm?
- What warranty comes with a replacement pump?
- Would you recommend a battery or water-powered backup for my home?
- Is my current pump sized correctly for my pit and water volume?
- Do you see signs of a larger drainage issue I should address?
Common questions
- How often should a sump pump be tested?
- Many plumbers suggest testing it a few times a year and before rainy or snowmelt seasons by pouring water into the pit and making sure the pump starts and shuts off normally.
- Why does my sump pump run all the time?
- It could be a stuck float, a failed check valve letting water flow back, a high water table, or a pump that's too small. A plumber can figure out which.
- Do I need a backup sump pump?
- It depends on how much damage a failure would cause and how often power outages occur. Finished basements and areas with frequent storms are common reasons people add one.
Related topics
- Burst and Leaking Pipes: What happens when a pipe bursts or starts leaking, what to do first, and what to ask an emergency plumber before work begins.
- Clogged Drains and Sewer Lines: How drain and sewer clogs are diagnosed and cleared, warning signs of a main line problem, and questions to ask a plumber.
- Toilet and Fixture Repairs: Running toilets, dripping faucets, leaking shutoff valves and fixture replacement: what a plumber does and what to ask.
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