I've seen a post similar to this before, so I'll try to get everything out of the way that I can.
I live near Wilmington, NC, USA in a home I recently purchased that was build in 2004. It is on a raised slab and there are no obvious plumbing concerns. As you can tell it is currently the middle of July, I have noticed this problem since the end of May of this year when I moved here. I tell you this in case these things may factor into the replies.

The cold water in all of my taps including my outdoor spigot, is between 78.6°F - 79.1°F after about 15 seconds in the low 70´s. I have tried shutting off the hot water at the water heater to see if that makes any change in temperature. Once I shut off the water leaving the water heater, I had no water in either of my bathroom's showers unless I also turned on the water in that bathroom's sink. The water still came out too warm.

This may seem like something trivial, but I keep rare and exotic freshwater fish. I need constant supply of cool, fresh water. My water-changing apparatus could heat the water, but not cool it because of myriad reasons. I have lived in different places, even the same county, and been in this hobby since the 80's but never had this issue. Is there a work around or something that I am missing?

Thank you

you are missing that the municipal supply comes from a tank elevated and baking in the sun

you are missing that your main is probably buried 12-18" deep and the topsoil is WARM

you are missing that you may be close to said elevated tank

you are missing that it is SUMMER

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The showers are probably pressure balanced, so when you turned off the W/H supply, the shower valves detected the loss of hot pressure and shut down the cold flow through them. When you turned on the sink faucet, if it was a single handle faucet, you might have backfed into the hot piping, the shower valve sensed hot and cold supply pressure, and returned functionality. If you want want/need cooler incoming water, maybe divert the incoming supply pipe, to a large coil of piping buried deep in the ground, using the earth as a heat sink.

Can you get the cool water you need from your refrigerator's water dispenser?

I've tried, but I need about 300 gallons a day and cooling with ice can cause pulmonary embolisms in the fish.

@bernabeu Thanks, especially on the summer bit. I'll make sure to take of my parka. Guess I set myself up to be trolled.



Edited 3 times.

Do your neighbors get cold water? If they do, you might have a cross-connection between the hot & the cold somewhere, most likely at a single-handle fixture. If your neighbors are all getting 79 degree water, it's what Bern said.

@geomyth,

i have EXACTLY the same situation

tepid bathwater cold water supply in the summer

gnome, not troll



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638