Sudden loss of hot water pressure in entire house

More likely the problem is some minerals or scale broke loose and traveled to where it was trapped in a bend or tee. Shut off the hot water tank, and the cold water to it, open a far hot water tap, and open the drain to the tank. With a little luck, water will run back to the tank, flushing the blockage to the tank and out the drain. If that doesn't help, try opening both the cold and hot at a mixing faucet, and holding your hand over the outlet to force cold water back to the tank.

If that doesn't work, you may have to start breaking pipe joints. If the hot water goes down after coming ot the top of the tank, the elbow at lowest point may be the problem.

THANK YOU FOR YOUR IMMEDIATE and thorough response!
I will try that.
More info: When I first turn the hot water on (closest fixture from hot water heater is tub) I notice the hot water will run with good and consistent strength for about 90 seconds, and then a very sudden drop in pressure to almost a trickle. I was able to reproduce this 3 times in the last few hours. Does this give you any more ideas? If something was caught in pipe, I would never have a good flow right? Versus a flow that only flows strong for x time? Thanks!

If the restriction is at the top of a vertical section, it may take time for the crud to collect at the top again.

Something has disturbed the mineral built up on your pipe walls or your pump is pumping sand or soil into your system. The reason you can get a good stream a that cuts off after a few seconds is that when the faucet's closed the clogs falls back down the supply. Then when you make a draw the water brings it right back up and clogs the faucet. You have to take apart the faucets and flush out the system from the mains through the branches and supplies. If the entire house is affected you may want to call in outside help. Good luck, Tom

I called a plumber. Since pressure problem existed all over house at every fixture and washing machine/dish washer/etc., we tested pressure coming into house from well pump using gauge on water well tank inside house. Gauge showed only 32 lbs coming in from well on a 40-60 which explained our lack of pressure. Problem either crack in pipe from house to well, or well pump. Dug up the well head outside house. Using compressor filled pipe again and now gauge inside house shows a solid 50lbs sustained pressure without leaks on pipe leading from house to well. Only thing left suspect is the well pump. Plenty of water in well - 500 ft. Filled with water on a 600 ft. Well. Perhaps the staging is off on the pump or it is going bad in some other way. Thanks everybody for responding!
- kathy

Hi Kathy,

Why did they dig up anything and use compressed air to test the integrity of the lines when all they had to do is run the pump until it reached cut out pressure, shut the house shut off,turn off the pump at the breaker box and watch the pressure gage. A fast drop in pressure would indicate a leak in the service line. Has anybody thought to increase the pressure at the control box? Not that I think your plumber missed the boat but let me show you how to increase the pressure.
Your pump has a pressure control. As a rule this will be Square D. First turnoff the power at the breaker box, then pull the cover off the pressure switch and you will see two spring loaded bolts secured with nylon nuts. One tall, one short. To increase the cut in pressure, turn the nut on the tall bolt down. To increase the cut out pressure,(that's the one that will give you more pressure) turn the nut on the short bolt down. This should give you the additional preesure you desire. This might just save you the labor and expense of replacing the pump. Good luck, Tom

Tom you are AWESOME and thank you!
Let me see if I can rearticulate all this back to you - since I'm not a plumber but an Internet engineer.

Initially he did not use the compressed air. Initially he did just what you said I think; ran the pump until it reached cut out pressure, I watched him shut the house water off (turned the little red handle on the copper pipe), turned the electricity to the pump off at the pump breaker box, and watched the pressure gauge. I believe this is when he saw the needle go down to 32 lbs. I think I heard him say that the pressure was leaking and we weren't getting up to 50 on a 40-60 switch and that meant possibly a leak in the line or a problem at the well pump side. I saw him clamp a volt meter to the electrical breaker box at the base of the house water tank, turn the house water off and look at a voltage meter and he said he saw the pump was still pumping at 7 amps (?) and I read the breaker box sticker on cover which said 6.4 amps. He said the pump kept pumping because the pressure requirement was never being fulfilled so the pump thought it was supposed to continue pumping....either the pump was working as designed and there was a leak in the supply line, or the pump was pumping even though it shouldn't be.

He said perhaps this might be either be a leak in the supply line, or if we're lucky some loose bracket at pump well side or something else on pump end and we tried to eliminate the supply line as a problem. He used the compressed air as a final test and after the compressed air test he still said we're at 32-35 but not to even 40 lbs.

At this point he said we then needed to check the well side for a malfunction but we could not dig up well head because of 4 feet of snow and dark out, so I took the weekend to dig it up for him to access by today (Tuesday.)

> Has anybody thought to increase the pressure at the control box?
Actually the pressure in the house has always been just great. This was a change I noticed suddenly - within a day or two went from 'great' to 'something feels wrong with the pressure'. THANK YOU for the directions on how to increase the pressure though for future if I ever need.

Today we accessed the well head, lifted it, and he did some things with gauges that I couldn't see, and he said there did not seem to be a problem with the supply line from well to house which is good. But that since we still had a pressure problem perhaps the pump itself wasn't pumping at the rate it needed to. He left to investigate pump prices...3/4 hp 230 volt 5 gallon well pump.

Oddly enough, after he left, I took a shower to cleanup after being in the dirt. The pressure seemed fine now. Hmm. I went to the jazuzzi where I was always able to reproduce this problem...turn on water and wait 90-120 seconds and it goes from full flow to WHAM - trickle. Well - this time I turned on jacuzzi and it ran full flow for over 12 minutes when I stopped it. Turned on washing machine - no problem. Dishwasher - no problem. All sinks and flushed all toilets - no problem.

I'm wondering what the problem was - and if I still do have a problem. I will wait a few days to monitor this behavior before deciding our next move. Wondering if our troubleshooting on the well pump end might have dislodged something that had the pressure obstructed? (Our efforts included us lifting the 'screw pipe' (?) up and clamping it so it wouldn't fall back down into well - while he retrofitted some valve devices he used.

Everything seems fine now. Strange. Wonder if I have a problem that will resurface.

Thoughts Tom?
- kath

Hey Kath,

Untill I read your last part I was about ready to point a finger at a faulty impeller in your pump but they don't fix themselves.
Tell yeah whot will "fix itself" that I haven't seen mentioned yet. The check valve. If it were stuck in the open position then then pump wouldn't have anything to pump against and all the pressure would go back down into the well and the pump wouldn't shut off. Also you would lose pressure once the pump was shut off at the breaker box. SNAP! The check valve freed up and the pump now pumps to pressure. I don't pretend to be a pump expert. In the Tampa Bay area pumps, septic tanks, water softeners and heating systems are separate trades. But in the course of running service calls I've been exposed to pump problems. If I had to check something before going into the hassle and expense of replacing the pump I'd look real hard at the check valve. Cheers, Tom

Check valve - ah. You are a thinker. Wish you were MY plumber. Thanks Tom. I'll run the 'check valve' theory by him. Meanwhile I'm looking up what the 'check valve' actually does so I might better understand. THANKS AGAIN. (my email is morank@optonline.net) if you wanted to not clog up the thread anymore but had anything else you would like to contribute. Cheers.