cooling city water in the summer

Question

First off, I live in Phoenix, AZ. This is desert here. I live in an area where people mostly have natural desert landscaping rather than lawns.

Now, this will sound really odd to folks who live elsewhere, but the house I'm in now does not get "cold" water in the summer. I can literally shut off my hot water heater and take a shower just from the cold water coming in from the city water line. The so-called "cold" water temp is somewhere over 110 for most of the summer. It's fine for most of the rest of the year, just not from May thru Sept.

I've lived in different parts of the city throughout my life, and this is the hottest "cold" water I've ever had to deal with. I think a big part of it is because the ground in this area is quite rocky and sandy, not much solid dirt. And it's dry as a bone.

Where you've got a water main running under yards that have lawns that are watered regularly, the water seeps into the ground and cools the ground and whatever pipes are there. Hardly anybody in this area has lawns, certainly nobody along the route where my water main comes from.

Short of putting a 50 gallon water cooler into a fridge (the opposite of a water heater), I'm wondering if anybody has any ideas about how I might rig up something that could cool the water coming into the house by 20-30 degrees?

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UPDATED 12/10/22

So I forgot about this post and just stumbled upon it again, although I haven't solved the problem yet. It's now winter in Phoenix, so I need some hot water mixed into the cold so it's comfortable. We actually get cold water from the tap from Sep thru May!

Most of the replies seem to be from people who think what I'm saying is as unbelievable as you telling me that you have to worry about water pipes in your walls freezing up. A "freeze" warning here means we have to put sheets over some of our shrubbery for the night. Nobody's pipes freeze here. Are you sure you don't have a refrigerant leak in your A/C somewhere? Trust me, the "cold" tap water from the city has been measured at 112º at times in my area. And the outdoor temps really do get as high as 125º here in the summer!

Anyway, I've come up with this working idea and I'm curious what sort of mechanical ideas you can think of. (I'm a software geek, not much good with this kind of thing.) If I'd be better off making a new post for this, let me know.

I'm thinking of getting something like this from Amazon or Home Depot: Rain Bird T63-500S Drip Irrigation 1/2" (0.634" OD) Blank Distribution Tubing, 500'

By my calculations, a coil of that should hold about 8 gallons of water that would weigh 67 lbs. If I were to build some kind of frame to simply expose it to the air, perhaps hanging from the ceiling above the tub, it would settle to an ambient temp of around 85º. I use a 1 GPM shower head. Using a splitter that can let me send some of the water coming to the shower head into this coil, then mixing it back into the original water flow, could reduce the temp to around 95 degrees for at least 10 minutes, which is about how long it takes me to shower. Worst case, I'd get 8 minutes of a nice cool 85º shower before it went back to "almost scalding hot". :)

What's the best way to suspend 500' of tubing like this from the ceiling with enough space between the coils to allow air to flow? The space is above a normal sized porcelain over metal tub. Would you just hang it from the ceiling joists? or maybe put some metal poles in the corners to support it? I'd be worried about it sagging in the middle or just falling down. In the cooler months, I can drain it since it's not needed.

Also, the tub is on the most exterior part of the wall, and there's no crawl space above it in the attic. So getting up there to do anything is a non-starter short of tearing the roof off.

NOTE: this is not a problem unique to my house or my street. Most restaurants and commercial properties that do not run their cold water lines through their chiller system will have "cold" tap water that's between 95 and 100 degrees. I don't know where folks think it's supposed to get cooled down when the ambient temps outside are well over 100, the ground is mostly covered by cement, asphalt, and bricks/blocks, and underneath is colichi, sand, and clay. We get rain during the monsoon from early July thru Sept, and it's mostly at night. It does not soak into the ground, but mostly runs off. After a rare afternoon rain storm, the ground is dry in an hour.

It's clear that most people who don't live here cannot comprehend water coming out of the "cold" water tap at nearly 100 degrees. I cannot comprehend how anybody lived here before A/C was invented!

Answer 1

Very common in tropical Australia, not a big deal. The ground gets hot in summer and even though the street pipes are six feet underground the water can scald. Every summer we turn off the power to the hot water storage tank, it then becomes the cold water supply. If we use too much "cold" water the tank warms up. The house has an evaporative cooler and the tank is positioned inside the house and is cooled.

Answer 2

I have lived in Phoenix since 2006.

Here's a solution I found:

• Get a large metal colander
• Get a rubber/plastic bowl about half the size of the colander then freeze water in that bowl
• Find a way to hang the colander under the shower head
• Place the chunk of ice in the colander and let the shower water run over the ice and sprinkle through the colander down on you.

It actually works!

Answer 3

1. Exclude a crossover problem in the shower valve as described by @Paul Logan above. Test the temperature of the incoming city water say at an outside faucet.

2. If the incoming city water really is 110 F, then make your own cool water (say 80 F) by the batch by putting enough ice into a bucket with 1 or 2 gal of water. Take a quick shower using a low flow shower head say 1 gal/min using the house (hot) cold water to get clean (less volume of water means less heating by the water). Then as a final cooling rinse repeatedly dip a small bowl into the cool water and pour it over yourself.

3. Alternatively, get a camping shower and pour the ice cooled water into the reservoir and spray it over yourself as a final rinse.

4. Get one of the old fashioned canvas water bags and hang it outside in the shade. Evaporation of water seeping through the canvas will cool the remaining water inside. Use that for the final cooling rinse.

Answer 4

Are you sure the water is really heating up in the ground outside your house? In my house (in interior southern CA where it is regularly over 100 in the summer/fall) we also have a problem with hot "cold" water, however I discovered while working on another project that the source was the plumbing inside the house.

It seems that the builder/plumber home-ran all the plumbing in the house to two huge manifolds in the garage attic space, complete with a ridiculous ~60 foot service loop in the 1.25" feeder pipe for what reason I am not certain. That created a massive amount of water just sitting there sucking heat up from that hot attic space all day.

A combination of cutting out the extra pipe, insulating the leftover, and insulating the attic space reduced the temperature of the "cold" water by over 30 degrees F in our case.

You might snoop around your service plumbing and see if you have a similar situation.

Answer 5

Is there any practicality of digging your own well to bring up water from deep in the ground? If you could do that then the water temperature would be closer to the average deep crust temperature of the earth.

Digging a well in most areas is probably limited to folks that have a certain minimum size of property. There are also many other local restrictions as well.

Answer 6

Perform a search for "undersink water chiller". You will find products in the $ 200 - $ 600 range retailed by companies like Amazon and Home Depot, capable of chilling about a gallon of water per hour, and capable of storing 2 - 3 quarts of chilled water.

Answer 7

This is just an idea, I guess it would be a variant on another answer suggesting you use the hot water tank for cold water supply part of the year.

Most well systems use a pressure tank in the basement of the home, the well pump fills the pressure tank from the hole in the ground, and the tank supplies the water in the house.

You could install a pressure tank that's simply fed from the water company supply, and in turn supplies the cold water for the house. (You could bypass the pressure tank to supply the water heater.) The pressure tank would serve as a simple cistern or reservoir where the water cools to your basement's ambient temperature. I believe it would cool faster than the water heater tank because it's uninsulated, and you could leave it in place year round. This should not be that difficult of a plumbing job.

You could even conceivably bury the tank in your yard or in your basement floor for better cooling. I am pretty sure that 4' underground the temperature is pretty cool, but you could easily core drill a small hole down a few feet and run a temperature probe to see before you did all that work.

Answer 8

Second hot water heater, used just for its reservoir.

If your hot water heater is not on and you try to get hot water, you get cold water. In my house, hot water comes from the hot water heater off the garage which keeps a tankful hot for when we want it. Cold water bypasses the hot water heater.

Get a second hot water heater. Have it installed with your cold water line as though it would be a hot water line. Don't attach the new hot water heater to the gas. Now you have a reservoir that will cool its water to your ambient basement temperature. Maybe you could even acquire a dead hot water heater and use it just for the reservoir - but not one full of mineral deposits.

I propose a hot water heater not being used for heating because I am not sure about all the internal stuff that lets these things regulate water flow. Hot water heaters have all that internal stuff and that stuff all still works when the heater dies and the water is cold.

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It occurs to me you could do a test run of this idea by turning off the hot water heater you have now and letting the tank cool down. Your "cold" water would stay 110F but if this idea has merit your "hot" water should be ambient basement temps.

Answer 9

I'm thinking of getting something like this from Amazon or Home Depot: Rain Bird T63-500S Drip Irrigation 1/2" (0.634" OD) Blank Distribution Tubing, 500'

OK

To get 4 liters/min (about 1 gallon) through 500ft of that pipe, assuming internal diameter of 8mm, you'll get a pressure drop of 4.5 bar (66 PSI), which is a showstopper.

If internal diameter is 10mm, that's 1.6 bar, or 23 PSI, which should be okay. So I'll assume 10mm ID from now on.

You can hang the pipe as a coil on a pole suspended from the ceiling.

500ft (150m) of 10mm ID pipe contains about 12 liters so we're quite off from 8 gallons, maybe you need a thicker pipe.

However once you have taken your shower and the pipe is filled with hot water (say 45-50°C) two things will happen:

Above about 50°C PEX pipes become much softer, so the whole coil hanging is probably going to sag quite a lot. That could make a handy gauge for how much cold water is left! I'm absolutely sure 20mm OD PEX pipe will not kink from this, but I'm not sure about the flimsy gardening pipe.

Then the huge surface area of the pipe will make an excellent heat exchanger with the ambient air in the bathroom. Given the water volume, the whole bathroom will heat to the temperature of the incoming "cold" water. So right after your shower, you'll have to towel yourself outside of the bathroom, otherwise you'll sweat buckets immediately. Then the bathroom will essentially become a steam cooker until the AC sucks out the heat, which could take a while.

I have actually experimented with this stuff: when we were laying the PEX pipe for the underfloor heating, we had to run hot water through it so it would soften and bend properly. So, with 20-30m of pipe lying on the floor and 55°C water, turning on the hot water tap, the whole room heated extremely quickly. And you're planning for a lot more pipe!

So I'm not sure it would be entirely practical (not mentioning the modern art sculpture hanging from the bathroom ceiling).

Personally I'd get a solar water heater, the kind of tank with an extra coil inside to circulate hot water from the solar panels. You can even use it in the winter to get hot water, assuming you get a lot of sun. The idea is to use a small circulator to pump water through the internal coil, then run this water through a heat exchanger placed in the AC duct... maybe a hydronic blower heater, or just a coil of pipe. So it would cool the tank slowly, over the whole day.

If you get cold nights in the desert, another solution would be to just put the large pipe coil outside, and use a circulator at night to cool the whole water tank.