Sand or grit in well water usually means the pump is set too close to the bottom of the well, the well screen has failed or worn, the well is being pumped harder than its yield, or a new well has not finished developing. A sediment filter protects the house but not the pump. Raising the pump, correcting the pumping rate or repairing the screen deals with the source.
Key points
- Sand wears pump impellers and clogs valves and switch ports.
- Some sand in a brand-new well is normal for a short time.
- A filter protects fixtures; it does not fix the well.
- Check the pump setting and pumping rate first.
Wellborne traces sediment problems on wells across Suffolk and the surrounding area. A little grit in a faucet aerator can seem minor, but sand is one of the things that wears out pumps early, so it is worth finding where it comes from.
Where the sand comes from
The pump is set too low. Wells collect some sediment at the bottom over time. A pump hanging close to the bottom draws it in, especially at start-up when the flow surges.
The screen has failed. Drilled wells in the Coastal Plain’s sand aquifers have a screen where the water enters, sized to hold back the formation sand. A screen that has corroded, been damaged or was the wrong slot size for the formation lets sand through.
The well is pumped too hard. Drawing water faster than the aquifer can deliver pulls fine sand toward the screen. An oversized replacement pump is a common trigger.
The well is new. A newly drilled well is developed, pumped and surged to remove fine material from around the screen. Some sediment in the first weeks is normal; it should fade quickly. Sand that persists means development was incomplete or the screen does not suit the formation.
Something has changed in the well. A cracked casing or failed grout can let surface sediment in, usually with cloudiness after rain.
What sand does to the system
Sand acts like grinding paste inside a pump, wearing impellers and diffusers until the pump cannot build pressure. It settles in pressure tanks and water heaters, clogs the pressure switch’s small sensing port, causing erratic cycling, and scores valve seats and fixture cartridges. An irrigation system carrying sand clogs heads and drip emitters.
Diagnosing the source
The questions are when it started and what changed. Sand after a pump replacement points to the new pump’s setting or flow. Sand during long runs or dry summers points to heavy pumping drawing the well down. Sand after rain, with cloudiness, points to the wellhead or casing. Sand from day one of a new well points to development or the screen.
When the pump is pulled, its setting relative to the bottom and the screen is measured, the pump end is inspected for wear, and the amount of sediment in the bottom of the well can be checked.
Fixes
- Raise the pump so it sits well above the bottom of the well and the top of the screen.
- Reduce the pumping rate with a smaller pump, a flow restrictor or a constant pressure system that avoids hard surges.
- Redevelop the well to clear fine sediment from around the screen; see well rehabilitation.
- Repair or replace a failed screen or casing; sometimes a replacement well is the realistic answer.
- Add a sediment filter or a spin-down separator to protect the house, alongside the source fix.
Shallow and bored wells
Shallow bored and driven wells often have no screen at all, or a simple open bottom, so fine sand and silt move more freely. In those wells, keeping the jet pump’s foot valve off the bottom and not pumping harder than the well recovers are the main protections.
Whatever the cause, write down what you see: how much sediment, its color, and when it appears. Those notes make the diagnosis faster.
Filters are protection, not a cure
A sediment filter catches what reaches the house, but the pump has already handled every grain by then. A filter that clogs every few weeks is telling you the well is producing a lot of sand, and the pump is wearing in step. Fix the source and the filter becomes routine maintenance instead of a weekly chore. For help finding the cause, call (757) 919-1972.