The borehole pump runs and nothing comes: prime, foot valve, or the air

A pump humming with a dry delivery line is the most misdiagnosed fault in the compound - the generator man blames the pump, the neighbour blames the water table, and the actual answer is usually mechanical, cheap, and knowable in a morning from the ground. Here is the triage a good pump technician runs, in order, before anyone quotes.

Fault one: it lost its prime

A surface pump does not suck water from the sky - it pushes air out of the line until the water column falls into it, and it needs water in the pump and suction line to start. An air leak anywhere on the suction side - a joint loosened by years of vibration, a cracked foot-valve housing under the tank, a valve cover gasket dried to cardboard - and the pump recirculates air forever, warm and useless. The tests a homeowner can run: check the pump's priming plug is full after filling and re-fill after a minute of running (water that just disappears is leaking past the foot valve down the borehole - the diagnosis announcing itself); then, with the pump off, listen at the suction joints with the line pressurised by hand - the hiss is the answer, and a new gasket or a tightened union is the whole repair.

Fault two: the foot valve has given up

Down at the bottom of the rising main, a one-way flap holds the water column in the pipe between pumps so you never re-prime a full borehole - and when its seal fouls on grit or its spring snaps, the column drains back, the tank runs dry between uses, and the pump's "no delivery" is really a lost column. The signature: prime holds when the system's off, but an hour of rest and the sight-glass bubble test starts again. The honest repair is a pull - the rising main comes up on a tripod or a small rig, the old valve gets replaced, and the filter screens get cleaned while the pipe is out - a pump technician's half-day, and the price of the call is not the pump's fault.

Fault three: the well has changed - the water table, the sand, the silt

Seasons move the table; years sand it up. A submersible sitting in now-silted depths pumps mud then nothing, the flow that once ran strong now surges, and the recovery test - run until the tank's empty, watch the recharge time against last year's numbers - tells you the borehole needs a developer's surging or a deepening, not a new pump. This is the one branch where the call genuinely stops being yours: the rig, the bailing and the decision are the water-geologist's territory, and a pump swapped over a silting hole is money spent to be wrong loudly.

The morning's order of operations

Prime plug open, fill, wait, run - then the two-ear test on suction joints. If prime vanishes into the ground: foot-valve branch, call the pull-man. If the well ran down with you: recovery test with a neighbour's meter or the tank's own clock. If it is the third thing - surging, sand, the smell of the deep - the rig's visit and this page are both cheaper than a new pump that fixes nothing.