Filters described as pump filters are fitted in three quite different positions, and only one of them protects the pump. The distinction matters because a pump running on abrasive water wears continuously and irrecoverably, while a filter downstream of it handles the same grit after the damage has already been done.
Downstream, which is the usual position
After the pressure tank and before all treatment is the standard domestic position, and it protects everything after it: the media tanks, the softener, any membrane, the ultraviolet sleeve, the plumbing and the fixtures. That is substantial and worth having. What it does not protect is the pump or the pressure tank, both of which have already passed the grit, and it is worth being clear about that before assuming the problem is solved.
Upstream, on the suction side
A strainer on the suction line of a surface pump, drawing from a tank, a stream or a shallow well, does protect the pump, because it sits ahead of it. The constraint is that anything on the suction side adds resistance where a pump can least afford it: a pump that has to lift water is limited by suction, and a blinding strainer can cause it to lose prime or cavitate. So suction strainers are kept coarse and are checked often rather than left.
Downhole, for a submersible
A submersible pump in a borehole cannot have a filter fitted in front of it in any ordinary sense, so protection is a well construction question: an intact and correctly sized screen matched to the formation, the pump set high enough in the borehole that it does not draw from the sediment layer, a shroud or flow sleeve to control where water enters, and a draw rate the aquifer can sustain. All of that is contractor work rather than plumbing.
Ask why there is grit
A well that has newly started producing sand has a cause, and every candidate degrades the borehole or the pump while a filter quietly handles the output: a failed or wrongly sized screen, a pump set too low, over pumping, or a collapsing formation. Have the well assessed first, then fit a centrifugal separator or backwashing tank for what remains, first in the train. Our replacement filter guide covers what belongs after the separator.
Questions people ask about water pump filters
Will a filter after the pressure tank protect my pump?
No. It sits downstream, so grit has already passed through the pump. It protects the treatment train and plumbing instead.
Can I fit a strainer on the suction side?
On a surface pump, yes, and it must be coarse and checked often, since a blinding strainer causes loss of prime or cavitation.
How do I protect a submersible pump?
Through well construction: a correct intact screen, the pump set high enough, a shroud, and a sustainable draw rate.
My well suddenly makes sand, what now?
Have it assessed. A failed screen, a pump set too low, over pumping or a collapsing formation all damage the pump.