Watts 8.5 in. W x 11.5 in. D x 8.5 in. H Pre-Pressurized Steel Water Expansion Tank-DET-5 - The Home Depot
Message to Our Customers


Model # DET-5

Internet # 100677607

Store SKU # 594885

8.5 in. W x 11.5 in. D x 8.5 in. H Pre-Pressurized Steel Water Expansion Tank

Watts 8.5 in. W x 11.5 in. D x 8.5 in. H Pre-Pressurized Steel Water Expansion Tank

This item has been discontinued.
The Home Depot no longer carries this specific product.

$40.92 / each


Model # DET-5

Internet # 100677607

Store SKU # 594885

You're sure to have hot water when you need it with the Watts Pre-Pressurized Steel Water Expansion Tank. Made from strong, durable steel, this tank can be used with gas, electric or oil heaters. An expansion membrane prevents air and water contact, with a rubber diaphragm that flexes when water heats.

California residents: see  Proposition 65 information

  • Compatible with gas, oil and electric heaters
  • Steel construction with a blue outer finish
  • Tank fitted with expansion membrane to ensure long system life by preventing air and water contact
  • Rubber diaphragm flexes when water heats
  • Maximum 150 psi
  • Maximum temperature 200ºF

Info & Guides

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Assembled Depth (in.) 
11.5 in 
Assembled Height (in.) 
8.5 in 
Assembled Width (in.) 
8.5 in 
Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Finish Family 
Product Type 
Expansion Tank 
Product Weight (lb.) 
5.1 lb 
Warranty / Certifications
Manufacturer Warranty 
Watts (the "Company") warrants each product to be free from defects in material and workmanship under normal usage for a period of one year from the date of original shipment. 


Rated 4.4 out of 5 by 33 reviewers.
Rated 5.0 out of 5.0 by Solves relief valve leaks from hot water expansion. After installing our new hot water heater (from Home Depot). I saw that when the tank heated the water, expansion of the water occurred, causing the relief valve to leak water. I installed a water expansion tank and the problem was solved. This also added a surprised second fix. . .. . the water pipes would knock when the toilets would shut off, this reduced that noise, sometimes eliminating it completely. . . cool. Follow the directions, air the tank prior to installation, to what your water pressure is. . . See the photo of our installation. . .as you scroll over the photo you will notice we were restricted on room - but it worked nicely. February 13, 2013
Rated 4.0 out of 5.0 by Installed without problems. Followed instructions, installed without problems. Note, if tank is installed sideways. Weight must be supported. June 10, 2014
Rated 5.0 out of 5.0 by Good DIY repair for closed water system After city water company made "updates" to our meter we started experiencing water coming from water heater T&P valve. Connecting water gauge to hose bib confirmed that after water heater turned off the water expanded from 60 lbs to over 100 lbs. Sized tank according to our incoming water pressure and water heater size on the Watts website and installation went without problems. The night before installation, I pumped up the bladder to match incoming water pressure. Next day the tank was holding so I started installation. After repair, reconnected water gauge and ran hot water to force water heater to cut on. During water heater operation and after turning off the gauge stayed on 60 lbs of pressure. No more dripping from the T&P valve. Wish city water company would have told us that they were installing back flow device. Be sure you measure incoming water pressure to be able to pressurize tank to the size. April 6, 2015
Rated 5.0 out of 5.0 by Fixed Hot Water Heater Relief Valve Leak My hot water heater's relief valve was leaking, and I replaced it. Unfortunately, the new one exhibited the same problems. A pressure gauge on the hot water heater determined that my home's water system was closed, and the relief valve was just doing its job. I installed this expansion tank on the cold water line going into the hot water heater. It lowered the pressure and resolved my dripping relief valve problem. Please be aware that you will have to pressurize this tank yourself, before you install it, based upon your water system's pressure. I had do 5-6 wraps of Teflon Tape to prevent it from leaking. January 8, 2014
Rated 5.0 out of 5.0 by Installation was a breeze. My old expansion tank sprung a leak. After I turned off the circuit breaker and main water and did some quick online homework, I purchased this tank as a replacement. I also purchased a water pressure tester, which you have to use to install the tank. Installation was very easy, requiring a bicycle air pump, tire pressure gauge to check your inflation, teflon tape, and a large wrench. This is handy info for someone who has to do an emergency repair like I did. September 26, 2012
Rated 5.0 out of 5.0 by Great Product This product is great. You MUST check the water pressure in your home with a pressure gauge ..(usually 55 psi ).. you can buy a spicket pressure gauge for about 10 bucks. Then you MUST put that much air in your tank if your water pressure is 55 psi then you need 55 lbs of air in the tank. If you fail to do this and hook it up as you buy it at 20 lbs of air in this tank it will fail pre mauture. You also must turn off water to your water heater once a year and open a faucet till it stops and check this tank pressure with tire pressure gauge once a year (write the water psi on the tank so you know how much air has to be in tank). If installed correctly this tank is great :)) February 17, 2012
Rated 5.0 out of 5.0 by required on a "closed system" After installing a new electric HWT and a pressure reducing valve I required a thermal expansion tank so the heated water volume could go somewhere. I inflated the tank from 20 psi to 76 psi (the same psi as I set the pressure reducing valve) before installing on the cold water line over the HWT using a copper T with a 6" extension of 3/4" copper pipe sweated to a 3/4" female threaded copper adapter. Wrapped the male 3/4" nozzle on the tank with Teflon tape and screwed the tank onto the female adapter and the maximum pressure on the hose bib is 80 psi. No more leaking of the relief valve or my Delta kitchen faucet from the past 160 psi with the HWT on. I have braced the cold water line at the copper T to support the weight of the TE tank which can be mounted vertically up or down and horizontal with adequate support. April 14, 2014
Rated 5.0 out of 5.0 by Solved my hot water heater T & P Valve leak problem My Temp & Pressure valve on my hot water heater would leak after using a lot of hot water, such as after a bath or shower. I replaced the valve and it still leaked. After doing some research on the problem, I determined it to be thermal expansion and purchased this product. After installation it solved my problem, no more leak. April 20, 2012
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