Well points are primarily used in mining, agricultural, and light industry to measure or control the level of a subsurface water-table. Well points are relatively easy to operate and they are low-cost, but this equipment has its disadvantages. Well point screens are designed to keep large debris out of the groundwater, but in the process clay deposits gradually build up on these screens for diminished groundwater flow. To keep your well point unit operating, you need to periodically unclog well point screens.
Consult the container on a liquid food-grade phosphoric mineral acid to see how much to use for well screen and filter cleaning. Every manufacturer dilutes its product differently, and you don't want to pour in too much acid right away.
Put on the rubber gloves. Pour in the recommended amount of acid into your well. When applied to a large body of water, food-grade phosphoric mineral acid gradually dissolves and doesn't create a hazard. However, in a pure form, the acid irritates human skin. If you spill any acid onto your skin while pouring, rinse with soap and water immediately.
Add acid 24 hours later if the well point screen is still clogged. The phosphoric mineral acid takes some time to eat away at the clay and clean off the metal screen, but after a full day you will know if you need more acid.