A private well system in a Missouri home has several places where water can be stopped, and most homeowners only learn where they are during an emergency. A short walkthrough, done on a calm day, lets you map each shutoff, label it, and confirm that it still moves freely. This guide covers the common points from the well to the fixtures and what each one controls.
Start at the well and the pressure tank
Water leaves the well through a line that runs to a pressure tank. Between the tank and the pipe that feeds the house, there is often a gate valve or ball valve on the tank itself, used to isolate the tank for service. Many systems also have a check valve near the pump or at the well head. You do not need to operate these during normal use, but you should know where they are so a service person can find them quickly. Keep the area around the well head clear and dry, and do not force any valve that has been stuck for years.
The main house shutoff
Look for the main shutoff where the water line enters the house, often in a basement, utility room, crawlspace, or near the water heater. Many Missouri homes keep this valve in a crawlspace or on an exterior wall, so check both inside and outside. This valve stops water to the whole house downstream of the pressure tank. Turn it slowly and watch the nearest tap for sputtering, because a fast close can cause a sharp knock in older piping.
Bypass and treatment valves
If your home has a water softener, sediment filter, or other treatment unit, look for bypass valves. These often appear as a set of three handles or a single lever. A bypass lets water flow past the treatment unit while that unit is serviced. Before you change any filter or adjust any salt level, confirm how the valves are set in normal use, and take a photograph of their positions with your phone so you can return them later.
Water heater and fixture stops
- The cold supply valve on the water heater, which lets you stop water to the tank without closing the main.
- Stops under sinks and behind toilets, which control a single fixture.
- Washing machine valves, usually behind the machine, with separate hot and cold handles.
- Hose bibs and outdoor spigots, each often controlled from inside by its own valve.
How to map your system
- Draw a rough sketch of the house with the well, pressure tank, main shutoff, and water heater marked.
- Tape a small label on each valve that names what it controls.
- Close each valve slowly, then open it fully, and note whether it leaks at the stem or the packing.
- Keep the sketch with your well records, and share a copy with anyone who helps you during a repair.
When a shutoff is not the answer
If the pump runs but pressure drops, a closed valve may be the cause, but so may a failing pump, a pressure switch problem, or a low water level in the well. If the pump runs constantly after you close a valve, the line may be leaking downstream of that valve. Shutting off water to the house during a power outage does not restore pressure, because the pump needs electricity to run. Test each valve one at a time, and call a qualified service provider if a valve will not hold, moves hard, or drips.
Safety notes
Turn off power to the pump at the breaker panel before working near the pressure switch or any wiring, and do not open electrical boxes unless you are trained to do so. If you are unsure which breaker feeds the pump, leave that step to a licensed electrician. Keep children and pets away from open trenches or pits near the well head.