Low flow and cloudy water: screen, sediment trap, or tank cleaning?

Run a flow test early on, with the household supply isolated:

- Measure the pump’s flow into a clean container for a fixed time.
- Then, if practical, compare that with flow available at the tank outlet before the pump, or check the pump inlet pressure or flow.
- Good supply at the tank but poor pump output points toward the pump, its strainer, or an air leak. Poor flow already at the tank outlet points more toward the outlet, sediment trap, or pre-filter.
- Keep the pump discharge directed somewhere suitable so cloudy tank water isn’t sent through household fixtures.

That comparison can prevent unnecessary tank cleaning and reduces the chance of stirring up sediment while diagnosing the restriction. The inspection interval will depend on roof debris and rainfall, but an annual screen and first-flush check is a sensible baseline.

Sample the pump discharge for turbidity during the isolated flow test, before reconnecting the household plumbing. Comparing a clean-container sample with the flow rate can help separate the possibilities:

- Clear discharge with poor flow points more toward the pump, its strainer, an air leak, or a restriction on the pump discharge side.
- Cloudy discharge with otherwise reasonable flow suggests sediment is reaching the pump from the tank outlet or suction side.
- Cloudy water plus poor flow can mean sediment is accumulating at the outlet, sediment trap, pre-filter, or pump strainer.

Discard the sample, don’t run the pump dry, and keep the discharge out of the household lines. If there is a drain point or service connection on the suction side, a small sample there with the pump isolated could show whether the water is already cloudy before it reaches the pump. Avoid opening the suction line if it will spill water or make priming difficult.

A cloudy discharge sample doesn’t reliably prove the sediment is coming from the suction side. A partially blocked pump strainer can release disturbed material when the pump starts, and worn pump components can also add debris to the sample.

I’d inspect and gently clean the pump strainer before drawing that conclusion, then take a sample from the tank outlet or sediment trap with the pump off and the water allowed to settle. If that low-disturbance sample is clear but the pump discharge remains cloudy, the pump or strainer deserves more attention. Keep the first sample out of the household lines either way.

cfurry45’s point about pump-strainer debris makes me wonder about a different source of the recent change: could roof-wash debris be getting past or around the inlet screen, especially after heavier debris loads? Is there a useful way to distinguish fresh material entering from sediment that’s been accumulating in the tank before deciding whether a full tank clean is warranted?

Comparing sediment near the inlet and outlet wouldn’t, by itself, establish how old it is or whether it caused the low flow. I’d keep the investigation focused on the screen, diverter, outlet and pump-strainer checks already discussed, following the system’s maintenance instructions. Avoid entering the tank or disturbing sediment just to make that comparison.

A simple log may help: note debris on the accessible inlet screen and what the first-flush diverter catches during routine checks, alongside heavy-rain dates and when cloudiness appears. A new increase after debris-heavy rain would be a clue to fresh input, not proof; sediment already in the tank can also be stirred up. You wouldn’t need to compare sediment inside the tank or disturb it.

Yes - an inlet screen mainly stops material larger than its openings, so finer roof-wash particles could pass through. Debris could also get around a screen that is loose, damaged, or not seated properly. Either is a plausible route for fresh material, but neither would show that it happened in this tank or that it caused the low flow.