Plumbing in the Home/Water pressure



I live in south Florida and my house is 2 story home with 4 baths. My issue is water pressure. We cannot use more than 1 shower in the same time. Using one is OK and when the 2nd is turn on water flow on 2nd floor bathroom drop significantly to just dripping. When we are using the 2nd floor shower alone, we notice the cold water flow pretty well but when we add hot water, the pressure drop. A gentleman from city building department came to check the outside water pressure and he said the water pressure from city line is ok and he suspect that the water heater is dirty and cleaning it could solve the problem. We try to clean it by releasing the water from the bottom and the water came out very clean and clear and we don't think the water heater is the issue. We would like to know what could be the issue and what could we do or what type of professional we should hire to solve the issue.
Thanks so much in advance for all your help!
Best regards,


Hello Amy,

There are a couple of details that were omitted. In order to make a call about this it would be helpful to know the age of the house and what type of piping is used for the water system. The determination that "the city's water pressure is okay" is a little bit vague. The general standard is between 40 psi and 80 psi to be considered functionally usable. If it is less than that, especially on a two-story house, there's going to be problems.

You can pickup a water pressure gauge for about $10 or $15 at Home Depot or Lowe's that attaches to a hose faucet so you can check the pressure yourself.

First, let me clarify something; Most people complain of low pressure when they are actually experiencing low flow rate. The flow rate, gallons per minute, translates to the amount of water you actually experience coming out of the fixture when it is being used. The biggest impact on flowrate is older, clogged up galvanized water piping in older homes. The flow rate is determined by the size of the pipe, specifically the inside diameter. As old galvanized piping is used, hardware scale and minerals begin to coat the inside of the pipe, reducing its effective diameter to the point that the water flow is severely impacted. This is most prevalent on the hot water side of the piping system.

If in fact the house is piped in copper piping, then it is just a matter of poorly installed system and undersized piping from the beginning. Copper piping is not subject to mineral buildup that galvanized steel piping is.

A qualified plumber is the one to call for a determination of these things and a possible fix.
Good Luck,

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Dana Bostick


Pretty much any residential plumbing questions. For "item specific" details such as a specific model of fixture, I will need to research and there may not be any useful information available. Note: I live and work in Southern California. We do not, as a rule, use hot water or steam heating systems, oil fired boilers or private water wells so my knowledge in those areas is pretty limited. There are others here on AllExerts that can probably answer those questions better.


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