Gritty water, a layer of sand at the bottom of a glass, sediment building up in your toilet tank. This is one of the more mechanical problems on a well system, meaning the fix usually isn’t a filter at all. It’s diagnosing why sand is getting into your water in the first place.
Four Actual Causes, Ranked by Frequency of Occurrence
Worn or Damaged Well Screen
The well screen is a filtering element near the bottom of the casing that’s supposed to keep sand out while letting water in. Screens degrade over years of use, especially in sandy or unstable soil formations, and once they’re compromised, sand gets a direct path into your water. This is one of the most common causes in wells over 15 to 20 years old.
Pump Set Too Low or Pulling Too Hard
If your pump is positioned too close to the bottom of the well, or if it’s oversized and pulling water faster than the aquifer can supply it, the drawdown creates enough turbulence to pull sediment in along with the water. This is a fixable positioning or sizing issue, not a well failure.
Failed Check Valve
A check valve keeps water from flowing back down the drop pipe between pump cycles. When it fails, water and sediment can settle back down and get pulled back up more aggressively on the next cycle, showing up as a sudden increase in sediment right after the pump kicks on.
New or Recently Serviced Well
A newly drilled well, or one that just had pump work done, often produces sandy water for the first few days to weeks as the formation settles. This usually resolves on its own. If it’s still happening a month out, something else is going on.
Diagnosing Which One You’ve Got
- Sand appears gradually over months or years: likely a slowly failing well screen.
- Sand appears suddenly right after the pump starts: check the check valve first.
- Sand gets worse during heavy household water use (multiple fixtures running): points to pump drawdown exceeding your well’s recharge rate.
- Sand appeared right after a new well or pump service: give it a few weeks before assuming there’s a real problem.
Fixes, From Cheapest to Most Involved
| Fix | Addresses | Cost |
|---|---|---|
| Spin-down sediment filter | Manages symptoms regardless of cause, doesn’t fix the source | $150 to $350 |
| Check valve replacement | Failed check valve pulling sediment back up | $150 to $350 |
| Pump repositioning or resizing | Pump set too low or oversized for well yield | $400 to $1,200 |
| Well screen replacement or well redevelopment | Worn or damaged screen letting sand through directly | $1,500 to $4,000+ |
A sediment filter alone treats the symptom and buys you time, which is a fine short-term move, but if the cause is a failing screen, sand production usually increases over time and eventually outpaces what a filter can handle.
What Sand Is Actually Doing to Your Equipment
Beyond the annoyance, sediment is abrasive. It wears down pump impellers, fouls softener resin beds, and settles in your water heater tank, reducing efficiency and shortening its life. Even if the grit itself doesn’t bother you, treating the cause protects every other piece of equipment on your system.
When to Call a Pro vs. DIY
Installing a sediment filter is a simple DIY job. Diagnosing whether your problem is the screen, the pump position, or a check valve requires pulling the pump and inspecting the well, which isn’t something to attempt yourself. Get a well contractor to run a camera inspection or pull the pump for a look before spending money on a screen replacement you might not actually need.
If sand just started showing up and nothing about your well was recently serviced, call a well contractor for a camera inspection before the sediment causes damage to your pump or water heater.