There can be many causes for the sudden appearance of sand in your water well. It is usually best to seek advice from a well driller or pump contractor to determine the source or cause.
If the sand or grit has been occurring for a long time it may need to be filtered or removed after the water well but before the house piping. If your well suddenly starts to pump fine sand, this may indicate that the well is filling with sand. Typically the well pump is set so it’s a minimum of ten to twenty feet higher than the base of the well.
When the pump is down near the base of the well, sand or grit and sediment can be drawn in. In old wells, the well shaft can fill up with fine sand and silt so much that the pump may start to suck in sand from the bottom.
Other sources for sand in water may come from the well screen becoming degraded and then allowing sand or sediment in from the gravel pack around the well screen.
When the well is drilled, it is lined with a steel, iron, or PVC plastic which is called a casing. The casing in the well shaft is installed by the well driller.
The well casing has spaces that allow water to penetrate the well from the surrounding groundwater and at the same time keep out sand and grit. This is called the well screen. Over time the well screen can become degraded and corroded and allow silt and sand to get into the well.
In some cases, the well pump can be too big for the well and pull sand in from the surrounding aquifer. Sand can cause rapid deterioration in the valves of the pump and cause build up of sand in the bottom of the well. In any case, a sudden presence of sand or grit is not a good symptom and the source or cause should be inspected.
If you see a lot of sand in your water it is best to contact your well driller to discuss the problem and possible ways to fix this issues. Sometimes the well contractor can pull up the pump 10 to 20 feet to eliminate sand uptake.
In some situations, a new casing may be advised. There are also special screens that the well contractor can install over the pump to keep out sand, although these are not feasible for some wells if the casing is very old or if the wells diameter is too small. If it is not feasible or possible to repair, a new well may be recommended.
Another solution is to install a centrifugal sand separator on top of the ground before the pressure tank. These remove sand and sediment by means of centrifugal force. The water spins inside the separator and the sand ends up in the bottom of the separator. Once there, the sand can be easily drained out through a small valve opening at the bottom of the device.
An alternative to the centrifugal sand separator is a filter screen with a small valve found at the bottom of the filter. The screen filters out the sand and grit and can be cleaned out by opening the ball valve and flushing the filter. These filters must not be too fine because they can result in pressure drop. Generally, a 60 or perhaps a 100 mesh screen works well in straining out most sand and grit. These types of filter screen are installed after the pressure tank.
Both the centrifugal sand separator and the screen filters have manual ball valves that allow you to flush out the sand. If you use a lot of water or have a lot of sand in your water, it may require frequent cleaning in which an automatic flush valve can be installed. These valves turn on for a few seconds and flush out the accumulated sediment and keep the sand trap clean.