I have this water pressure tank system:

enter image description here

my questions:

  1. I am not sure whether it is a G.I. or stainless steel pressure water tank. How do I test what kind of material it is made of?

  2. There are so many rusty water coming from faucets.. Can stainless steel or G.I. rust inside it? I'm not sure if the rusts originate there or elsewhere.

  3. Recently when the water pump put enough water to register 30 psi (Is there a list pressure to set for corresponding tank volume?). It stopped runing and goes down slowly even if the output gate valve was closed. Which do you think is leaking? There is no leak at the water tank or water pump. It has no input check valve but for past 10 years there was no defect or pressure going down without use after it stopped pumping at 30 psi.

  4. The water inside is only 20% when water pump stopped pumping. I'm thinking of getting the Aquaflo pressure tank. Is it true it can hold 99% of water? It means the remaining volume of 1% will be compressed air, what do you think of the following?

"Aquaflo pressure tanks are 99% efficient. Conventional pressure tanks use only 25% of the water inside them. While a 42 gallon tank might look impressive, in reality, only approximately 12 gallons are used (“draw down”). With Aquaflo pressure tanks, 99% of the water is used. Thus, you can get rid of the excess size needed by conventional pressure tanks. This allows Aquaflo tanks to deliver the same performance while reducing it’s size."


The rust may be coming from your well casing. The newer tanks are much more efficient, I am not sure if they can actually hold 99% of there total volume because of the air required but they do allow for the bladder volume to be pushed out and can be much smaller than the old style you have now. I just changed my jet pump out for a submersible, the lines from the well and jet had quite a bit of rust and I believe this is from the well casing as we have almost no iron in our water samples that were tested. So a new tank may not solve the problem. One thing I have noticed with the new style is the water is taken from the bottom of the tank where the style you have the water is taken from the side and you may or probably will find the bottom of the tank is filled with silt and rust. On the tanks I have replaced I have added "string filters" to take this sediment out, they have to be changed every couple of months but this keeps our airators from getting plugged and can extend the life of washerless faucets it is the small debris in the water that really can chew up the little o rings. Is it a good idea to update your tank I say yes since you are having problems. As far as trouble shooting you may want to check your foot valve (at the bottom of the well) this should not be two hard since you have a shallow well based on your pump style. Foot valves do get debris in them and leak or just wear out. If you turn the supply to the house off and your pressure still drops with no output the foot is the place to look, I have had the poly line break or crack on several occasions and when checking the foot inspect the poly also.


Visually the system looks dated

  1. The tank itself is glass lined you can test this by using a magnet. Lower grades of stainless steel are still magnetic but only slightly, due to them being only moderately ferrite. Glass lined tanks are only good for 10 to 15 years if maintained well they can see 20 but it's very uncommon. By the look of the tank there's no anode in it therefore it would only last 10 years max

  2. Glass-lined tanks can and will indeed rust and they will Rust completely through if given enough time. Low grade stainless is capable of rusting but usually to a lesser degree.

  3. Losing pressure without a leak is most likely due to the water going back down the pump. It's possible that there is a leak in the tank at the top weld allowing a small amount of air to escape without being evident because water hasn't made it there yet the possibilities are endless.

  4. Bladder tanks such as the Aquaflow mentioned are far superior to standard expansion tanks. The downside is perforations are possible rendering your expansion tank relatively useless but with proper maintenance perforations are very uncommon.

  • How do you know the tank is glass lined? – Jtl Mar 12 '19 at 10:39
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    I don't for certain. Indications point to it such as rusty water, it age and the welds visible at the top of the tank. Welding stainless is difficult in comparison to steel and results in a much more professional looking weld. – Joe Fala Mar 12 '19 at 10:45
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    Anode's are factory installed and feild replaceable usually in the form of a long rod inserted in the top of the tank. It would look like a threaded plug from the outside. It's job is to be a sort of sacrificial lamb to slow corrosion of the tank. – Joe Fala Mar 12 '19 at 10:58
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    They do(bladder tanks) hold a very high percentage of water volume. I can't say the exact number but if the Aquaflo is claiming 99% there is very little reason to doubt it. – Joe Fala Mar 12 '19 at 11:05
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    There's a physical separation between the air and water in a bladder tank. On the air side without any water in the system it's pressurized to such a degree that when your system is up to pressure all of the air is compressed greatly. With a standard tank at some point the air will start to dissolve back into the water. – Joe Fala Mar 12 '19 at 11:19

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