Hi. This is my first time to the forum group, so I don't know how to start. We bought this house in 2000. It is now around 28 years old. For about 2 months now, every time you take a shower, there is hot water, but it lasts up to 5 minutes. The water in the toilet tanks used to be cold, now they are running hot water. The hot water heater was replaced last year. Right as we speak, I am in the process of changing the toilet mixing valve, hoping that that might be the cause for all this. Can someone please help me if this doesn't fix my problem?

What toilet mixing valve. What kind of water heater do you have? Do you have a stand alone water heater (gas or electric) or do you have some kind of boiler heating system that is also providing domestic hot water. Do you have a hot water re-circulating line on you water heater?

Im curious too. Never seen a mixing valve on a toilet, are you maybe replacing the fill valve? Also, you say that the hot water pressure depletes after five minutes. Does the actuall pressure of the hot water go down, or do you just run out of hot water and pressure stays the same. Please give us some more details about your systema and we will do our best to help. Take care.. Lee.

If he's really talking about a toilet tank mixing valve, (see image) and not a ballcock they can be adjusted for less hot water.
Toilet tank mixing valves were installed to stop condensation. This was a problem way back when bathrooms weren't air conditioned. Back then you had only two options. You could warm the water in the tank so it wouldn't sweat or you could wrap the tank in one of those horrible looking fuzzy tank covers.
And that children, concludes our history lesson for today.
Mike! You have two options here. You can adjust the mixing valve to give the tank less hot water or you can close the hot water side completely. Answer Harolds and Lees questions and we'll see if we can help because I'm not all that sure a toilet tank will run you out of hot water. I want to see more details!
Cheers, Tom

Ok, sorry that I never answered anyone yet. I didn't know that the responses would come back so quickly. I was only alerted about a new message recently. Lets see if I can attempt to fill in the blanks. Speedball1, the image that you have there is the toilet mixing valve (or toilet mixing beacon). That is the part I had replaced. Unfortunately, after replacing it, I had hot water that stayed for about 7 minutes in the shower, and 10 minutes after cleaning the dishes at dinner. Hkstroud, my hot water heater is an electric hot water heater. It was bought around February of 2008. It is a 50 gallon tank. I have never had this water problem until recently. You still have water pressure on both the hot and cold, but the water turns cold after 5 minutes. I thought that after reading a forum about a possibility of there being gunk in the bottom of my hot water heater, I drained out the water from my heater and tried to start fresh.

How do I make sure that only the cold water goes into the toilets? The hot water seems to have been happening in the upstairs toilet where the tank would fill up with hot water. Another thought that I could have is that the valve that leads to the excess water has been running. Could this also be why the hot water runs out so quick, because it keeps draining out as excess water?

Another thought that I could have is that the valve that leads to the excess water has been running. Valve that leads to excess water. Hmmm!
Never heard that one before. Please explain.
When you replaced the toilet mixing valve what did you do with the hot water line?
Ya crossed something some where. What was it? Regards, Tom

I personally would get rid of the mixing valve, and just supply the toilet with cold water, or add a shuttoff valve strictly for the hot water side of the mixing vavle and turn it off completely. This will eliminate toilet as problem.

Other than that, the first thing I would do is check the heating elements in the water heater. If one of the elements is burned out, you will get very little hot water. Heating elements in electric water heaters are cheap and easy to replace(with the right tool). There are only two, one on top and one on bottom. To test them, turn power off to water heater, disconnect leads to elements, and do a resistance test between the two lead on each element. Please let us know how you make out. Another option is the dip tube in the water heater, but I would start by testing the elements first. Good luck and please keep us posted. Lee

When you periodically flush your heater do you get bits of white creamy stuff, could also be a broken dip tube. You do flush the heater perodically, right?

ballengerb1, I have noticed 2 little creamy lumps in the toilet tank. Before I noticed about the water in the toilet tank was turning warm, I noticed that the water was turning cloudy or almost all white. I thought it was because I had poured some bleach into the tank to clean the toilet. What is a dip tube, and where is it located?

mygirlsdad77, how do I check the heating element in the electric hot water heater? I thought maybe it was that the pressure had to be adjusted on the valves, but both valves are fully open. On the hot water heater, the temp is set to very hot. The toilet water is now filling up cold water.

speedball1, don't worry about that remark about what I said about the excessive water. I checked it out on the water heater, and saw that it is like the reservuar or something else. It is located on the upper part of hot water heater (one of the 2 drainage valves). On the hot water heater itself, it says to maintain a safe water heater to not seal off this valve.

Could this mean something on the hot water heater went? It is a shame because the other one that we had lasted a very long time (possibly about 9 or so odd years, not fully sure because we lived in the house for 8 years, and the hot water heater has been there longer before we replaced it last year).

Thank you all for your responses. Really looking forward to solving this problem.

Check out post #7 for checking elements. If you do not feel comfortable doing this, a pro can do it in a matter of minutes. Also, if you decide to have outside help come in, I would have them check the dip tube while they are there. Lee.

Ps, the vavle near the top of water heater is a pressure/temperature relief valve and should in no case, ever be plugged or capped.

Mike, flush you heater through a strainer or screen and tell me what you catch. The creamy bumps are deteriorated dip tube and could be your whole problem if present.