Symptoms
- Pump cycles on and off very frequently or runs nearly nonstop
- Motor sounds like it's working hard or overheating
- High electric bill increase noticed alongside the behavior
Likely causes
- CommonFailed or missing check valve on the discharge pipeWithout a check valve, water in the discharge line flows back into the pit after each cycle, forcing the pump to run again almost immediately.
- CommonGenuinely high groundwater or heavy ongoing rainDuring major storms or in areas with a high water table, frequent running can be normal and expected.
- PossibleFloat switch stuck in the 'on' positionA jammed switch tells the pump to keep running even after water level drops.
- PossibleUndersized pump for the amount of water entering the pitA pump that can't keep up runs continuously without ever fully emptying the pit.
What to do
- Watch the pit water level through a full cycle to see if the float is moving freely and the pump actually shuts off between cycles.
- Check the discharge pipe for a check valve, and install one if missing, or replace it if it's failing to hold water back.
- Inspect the float switch for obstructions or debris preventing it from resting fully down after pumping.
- Consider whether recent heavy rain or a naturally high water table could explain frequent, but otherwise normal, cycling.
- Compare your pump's rated capacity to typical inflow if this is a chronic issue, and consider a higher-capacity pump if it seems undersized.
- Add a battery backup system if frequent running increases the risk of failure during a power outage.
- Call a plumber if the pump seems to be working overly hard or making unusual noises, since it may be nearing failure.
Tools and parts
- Flashlight
- Bucket
Sump pump check valveSearch: “sump pump check valve”
Higher-capacity sump pumpSearch: “1/2 HP sump pump”
When to call a pro
Call a plumber to evaluate pump sizing or replace a struggling pump before it fails during a storm.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.