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+--- Thread: filter location (/showthread.php?tid=17196)
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filter location - Hunt Stoddard - 05-10-2016
I'm sure this has been asked before, but for catchment systems, what is the proper order of the filter, pump and pressure tank. Can the filter ever properly go before the pump, or should it be after the pump and before the tank, or after the pressure tank even?
RE: filter location - terracore - 05-10-2016
I believe the filters are designed to have water pushed through (after the pump) as opposed to being pulled through (before the pump).
The intake in the catchment tank should have some sort of sieve on it so the pump doesn't try to pull in something too big for it to handle (like a huge leaf or worse yet a dead rodent) and post pump would be the pressure tank and then the filters. If you try to put the filters before the pressure tank the pump cycling would probably ruin them. The "calmer" water stream post pressure tank is what the filters are designed for. If you want to add a UV system, it needs to be installed after the filters. Each brand is different, but the standards ones need a 5 micron filter before the UV system because any larger particles aren't guaranteed to be sterilized by the light.
In other words: sieve in catchment tank --> pump --> pressure tank --> sediment filter --> finer filter --> UV (if you have it) --> into house plumbing system
RE: filter location - MarkP - 05-11-2016
My floating intake incorporates a 30 micron pleated filter. The water gets sucked through that. Directly after the pump I have a 10" Sawyer PointONE filter which is a .1 micron filter. The water gets pushed through that. I do have a very small pressure tank after the .1 micron filter. I try to maintain a slight chlorine residual. Other than that I let er rip. I drink my water straight from the tap.
RE: filter location - hotinhawaii - 05-12-2016
A filter should always be after the pressure tank. Untreated water in the pressure tank will set and allow bacteria to develop. Even if it's uv treated and filtered water, they are not 100.00% effective at removing all biological contaminants. You don't want that water to stagnate anywhere in the system after the filters.
RE: filter location - Hunt Stoddard - 05-12-2016
Thanks for the info. I guess the strainers that are built into "foot valves" for traditional well pumps will work for that. I've seen foot valves inside catchment tanks, which I guess means you don't really need any external check valves (?). The idea that you're going to have stuff growing inside the pressure tank anyway, so you might as well have filters after them makes some sense to me.
I know some people who drink catchment. I think they have great immune resistance. .1 micron is still bigger than a lot of viruses, so your mileage may vary. I've drank a lot of spring water and surface well water in my day, so I'm not one to talk.
RE: filter location - terracore - 05-12-2016
Personally, I wouldn't drink catchment water that wasn't UV, reverse osmosis, boiled, or chemically treated. At least not here.
RE: filter location - MarkP - 05-12-2016
By it's very nature the water in a pressure tank does not sit for any length of time. Half of it gets changed every time the pump cycles. The entire volume probably turns over 10 times a day. My tank is only a few gallons so it changes out even more times than that.
I don't see any benefit to putting the filter before or after the expansion tank. In general you would put the filter so as to not see the highest spikes. In my case my pump does not have a very high flow rate. When I shower the pump runs continuously and it wouldn't matter where I put the filter because it would see the same flow rate.
I don't think it matters whether you are sucking water through or pushing it through as long as it is going the filter the same direction. I think that the filters are intended to have the water flow from the outside through to the inside.
Basically I have drunk the kool-aid as far as the effectiveness of the PointONE filter. In theory it protects me from everything except viruses. My isolated catchment system is not at great risk from viruses plus i dose it with chlorine when I remember to. I will post if I get any suspicious symptoms.
RE: filter location - Hunt Stoddard - 05-12-2016
Wait a minute, now I'm conflicted again. This seems to be a perennial controversy.
I think I'm going to go with terracore's order, just because for well pumps, the filter obviously goes after the pump. But I just told a woman I should move her filter to after her jet pump. It's been working ok with the filter first for several years. If it ain't broke...?
RE: filter location - kalakoa - 05-13-2016
don't think it matters whether you are sucking water through or pushing it through
It matters to the pump -- some (eg, those little DC diaphram pumps) don't have much suction, so the filters always go after the pump in that case.
RE: filter location - MarkP - 05-13-2016
I'm not trying to argue but I have one of those little DC diaphragm pumps and it has been sucking water from the tank through a 30 micron pleated filter for over a year now.