hi every one i have a question in f hi every one i have a question in f mostafashdeed (Mechanical) (OP) 4 Dec 16 14:35 hi every one i have a question in fire water tanks shall i put a strainer before the tank or after and why thanks in advance RE: hi every one i have a question in f DavidCR (Mechanical) 10 Feb 17 17:13 Yes and 1/2 no. Why do you need the strainer. The water is too dirty or a sprinkler/spray system requires it? Before the tank. Yes. But good engineering or the AHJ may ask you for special requeriments for it. The AHJ may see it as a requirement for the water supply system that me be out of NFPA rules and only give recomendations. Examples: If the water is public relatively clean, better not. If you are taking water from the sea, snails and other sealife may block the entrance and strainers will not be advisable, and special measures should be taken. If you are taking water from a penstock you will be required to use strainers in parallel and a customized maintenance schedule. After the tank. Depends. Only if really needed. It is on scope of rules so listed filters may be required and they will be more expensive than filters before the tank. Listed filters are in general bigger, since they requiere an open mesh area that can only be met with a bigger filter. So I prefer a pair of noemal filters before the tank than one after. If the tank have a space in the bottom for deposits, not neccesary.