Setup: Electric 53 Gallon Heater, installed in 2014 by previous owners. Location: Tampa bay, Florida, Home built in 1961, typical cinder block house.

WE purchase the home in December and all has been working great.

Issue: Very low hot water pressure in the entire house. Water begins when first turned on with an acceptable amount of pressure but quickly over a few minutes drops to very low pressure. Enough time for a 5 minute shower, if that!

We called a plumber out and they recommended to replace the water heater. They suggested there is probably a clogged line in the water heater itself?

What I have done: I have drained the hot water heater from the bottom of the tank for about 5 gallons, there was no sediment what so ever at the bottom.

Any ideas?

  • Do you have the same issue if the cold water is left for the same amount of time?
    – Narthring
    Sep 10, 2015 at 2:54
  • @apeek2901 we assume you have found your answer - can you post it?
    – Ken
    May 9, 2017 at 3:29

1 Answer 1


Your house was built at a time when galvanised pipe was common, the problem is most possibly your pipe has slowly corroded closed in 1 or more places, thus when you turn the hot off the pipe charges open and you loose pressure the longer it is on with a new water heater and old house that is what I would look at a switch over to Plastic with some of the new shark bites is not really that hard and you may get all the pressure you have on your cold by just replacing the main line worth a look and cheaper than another water heator that may end up with the same problem

  • 1
    I don't follow this logic. If the galvanized pipe were corroding shut, the pressure would always be low. apeek2901 described a problem that develops over the course of about 5 minutes.
    – Dave
    Nov 18, 2015 at 20:26
  • 2
    it seals all but a small fraction so you have pressure to start with but then it falls off, take a hose, turn the water so only a small trickle of water is flowing, now stop the flow out the end of the hose it may even take a minute or so but you will see pressure build, then let the water flow there will big a big burst of flow and it will diminish untill it is at the trickle level again, this is quite common with old galvy lines if they dont start leaking, trying to post a pic of pipe
    – Ed Beal
    Nov 18, 2015 at 20:36
  • Interesting. So in his case the flow restriction would probably need to be behind the water. I couldn't imagine the small amount of pipe between water heater and fixture storing enough pressure to last 5 minutes but if it's between the water heater and the street, you get the pressure of all the plumbing in the house plus the tank.
    – Dave
    Nov 18, 2015 at 20:45
  • Also, I second the recommendation of plastic (PEX) plumbing as replacement. The best fitting as of 2009 when I replace all my plumbing was the expansion fitting, which requires a special tool but isn't that much more difficult. There are numerous advantages to PEX.
    – Dave
    Nov 18, 2015 at 20:46
  • I typed "picture of galvanised pipe corrosion" it came up with many examples , I hope you look and try the hose thing it will make it clear that What I have explained can be the cause VS an almost new water heator as they said the cold was fine so the main line to the water heater
    – Ed Beal
    Nov 18, 2015 at 20:46

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