Rusting Pressure Pump

Hi,
I've got a problem that has stumped two plumbers-including a master plumber. We have a concrete rainwater cistern with pvc pipe. Ever since the house was built 1 1/2 years ago, the cast iron sta-rite pump and pressure tank began rusting- filling 4x10 whole house filters in two weeks with a red brown "sludge". We thought it was iron sediment from the cistern or, perhaps, "sahara dust" from the roof( in that we're in the US Virgin Islands). However, when we installed a "pre filter" before cistern water hits the pump- those filters came back mildly gray in color- totally unlike the filter AFTER the pump. We cannot figure out why the pump and pressure tank have rusted out this way. We even put a new pump in 6 months ago and now it is totally rusty inside. One consideration was mildy salty pool water perhaps somehow getting back into the house water pump but this has been carefully explored and it's not happening. PLEASE. Give us your idea on what could be rusting out the pump. We're putting in a plastic pump and pressure tank so this may solve the problem but we're all stumped as to what is going on here.

Thanks.
StJohnman

If it is sort of slimy, it might be bacteria; not an uncommon thing in a cistern. It might need a shot of chlorine, but it is likely to come back.

rusting pump PS

Hi,

Thanks for your response. Iron Bacteria usually shows up as rusty slime in the back of toilets from what I've learned and is not a problem in our home. Two things I didn't mention in my original post were that 1, the cistern water has a low ph in the mid six's and 2. sometimes we buy water which is desalinated sea water. I've wondered if the water had salt in it but no other homes we know of have our problem so we are totally stumped. There must be SOMETHING in our water causing two pumps in two years to rust but we can't figure it out. If were simply iron in the water, for instance, wouldn't it be precipitating in the cistern itself and show up in our new 1 micron "pre filter" ( before the pump)? It's only AFTER the pump that the red/brown rusty slime clogs the cartridge water filter. Any more ideas????

I have to assume your pumps have cast iron castings. The pump should be pre rusted if it's a good brand name pump as it should have been tested at the factory. Cast iron rusts quickly, but does not flake off even with low PH water, so I doubt it is the pump that is plugging these filters. If you used a real filter, this probably wouldn't be a concern. Those inline Big Box filters are meant to be changed all the time, just like the coffee filters with a MR. Coffee. They will give you the Coffee Maker as long as you keep buying the filters.

Get a real whole house filter which would start out with a 9" X 48" or larger tank with an automatic backwash head and the problem should disappear.

I would recommend staying away from plastic pumps and tanks. The quality will be the lowest.

bob...

Question for Bob

Dear Bob,

Thank you for your thoughtful response. One thing puzzles me. Why does a simple 4x9 cartridge filter put AFTER the cistern but BEFORE the Sta-Rite( a good cast iron) pump show minimal gray sediment but another filter put AFTER the pump shows a red/brown slimy sludge that fills up the filter in 2 weeks? How could it NOT be coming directly from the pump???
Thanks,

Norm

Sorry, I've been away with little to no internet access.

I have no idea why the filters are plugging up, but I don't recommend those in line filters and certainly not before the pump.

bob...

Wow...I'm not sure if you been reading my post about the IRB problem I have been having, but strangely enough, I also had a sta-rite jet pump with cast iron housing. I replaced it because it was starting to leak and it had rust inside the pump. Maybe it is a weakness among the sta-rite pump housings. I also live near the ocean and my neighbors do not claim to have this problem.

If you have an IRB problem, that's what is clogging your filters and quite rapidly I'm sure. You need to treat the IRB and forget about these inline filters. Believe me, that pump casting cant give off enough rust in a years time to plug even the best inline filter (if there is any such thing as a best inline filter). Sta-Rite and all the other Brand name cast iron pumps out there are basically the same design and if they had the problem your describing, they would have been out of business years ago.

bob...