A water heater expansion tank protects your plumbing from the pressure that builds when water is heated. Below, we explain how an expansion tank works, its key benefits, and the signs your home may need one.
Because water expands when heated, excess pressure inside a water heater tank needs to escape. In the past, the pressure would force water in the tank to drain back out into the water supply where it came from.
Today, the water main is designed to prevent the backward flow of water, known as backflow, by means of a check valve. The check valve prevents wastewater from inside the home from returning to the water supply, where it could contaminate the supply of fresh water.
Key Benefits of a Water Heater Expansion Tank
Adding an expansion tank to your water heater system is a small investment that delivers several practical benefits:
- Protects your water heater: controls pressure that can stress the tank and its connections.
- Stops relief valve dripping: prevents pressure spikes that cause the temperature and pressure relief valve to drip or discharge.
- Safeguards fixtures and appliances: reduces strain on faucets, toilet fill valves, and the valves on your washing machine and dishwasher.
- Reduces repair risk: helps prevent leaks and premature wear caused by repeated pressure swings.
- Supports code compliance: closed plumbing systems typically require thermal expansion control under modern plumbing codes.
- Seeing water drip from your relief valve? Read our guide to the water heater TPR valve to learn what it means.
How a Water Heater Expansion Tank Works
A water heater expansion tank is a small secondary tank that connects to the cold water supply line near your water heater. Inside, a flexible diaphragm separates the water from a cushion of pressurized air. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excessive water pressure.
If water pressure gets too high, it can damage valves in plumbing fixtures, joints in supply pipes, and the water heater itself. Expanding water from the water heater flows into the expansion tank, where the air cushion compresses to absorb the extra volume, relieving water pressure in the system.
Have more questions about water heater expansion tanks? Call the experts at ABC Southwest at (941) 225-2182 or request water heater service online for answers!
What If My Water Heater Doesn’t Have an Expansion Tank?
Many homes that have a check valve on the water main do not have an expansion tank, since one wasn’t always required by plumbing code. This may or may not cause excessive pressure buildup, depending on the specific design of the plumbing in the house.
If you are noticing any of the following signs, it may be wise to add an expansion tank. It can be low-cost insurance against more costly damage to your home’s plumbing system.
- Washers in plumbing fixtures deteriorating rapidly
- Water dripping from the water heater’s relief valve
- Banging or noisy pipes when hot water is used
- Higher-than-normal water pressure at faucets
A licensed plumber can test your water pressure to confirm the cause and recommend the right fix.
Ready to install a water heater expansion tank in your Sarasota-area home? Schedule water heater expansion tank installation with the water heater experts at ABC Southwest!
Frequently Asked Questions About Water Heater Expansion Tanks
What is a water heater expansion tank?
A water heater expansion tank is a small tank installed on the water supply line that absorbs excess pressure created when water heats and expands inside a closed plumbing system.
What are the benefits of a water heater expansion tank?
An expansion tank prevents pressure buildup by allowing heated water to expand safely. This protects the water heater, plumbing fixtures, and pipes from damage, helps stop relief valve dripping, and reduces the risk of leaks.
Do I need an expansion tank on my water heater?
Homes with closed plumbing systems, such as those with a check valve or backflow preventer, typically require an expansion tank to control pressure and meet modern plumbing codes. A licensed plumber can test your water pressure and confirm whether your home needs one.
What happens if a water heater does not have an expansion tank?
Without an expansion tank, increased pressure can cause relief valves to drip, shorten the lifespan of plumbing components, and potentially damage the water heater or pipes.
Can a failing expansion tank cause plumbing problems?
A failed expansion tank can lead to excessive pressure, leaks at fixtures, water heater relief valve discharge, and increased stress on the plumbing system.
Where is a water heater expansion tank installed?
It is typically installed on the cold water supply line near the water heater, where it can absorb the pressure created as water heats.
How long does a water heater expansion tank last?
Most expansion tanks last roughly 5 to 10 years, depending on water quality and system pressure. If the internal diaphragm fails, the tank can become waterlogged and stop absorbing pressure, so it is wise to have it checked during routine water heater maintenance.
Helpful Water Heater Expansion Tank Resources for Homeowners
- The ABCs of Plumbing: Water Heater TPR Valve
- How to Flush a Water Heater
- Water Heater Repair
- Plumbing Maintenance
Get Help With Water Heater Expansion Tank Installation in Sarasota & Southwest Florida
If you’re unsure whether your water heater needs an expansion tank or you’re noticing signs of excess pressure, the licensed plumbers at ABC Southwest Plumbing & Air Conditioning can help. Our team inspects your system, confirms code requirements, and installs expansion tanks correctly to protect your water heater and plumbing system.
We also offer water heater repair and plumbing maintenance, and Ultimate Advantage Club members enjoy regular maintenance appointments and no service call fees.
Call (941) 225-2182 or contact ABC Southwest today to schedule water heater service and get expert guidance for your home in Southwest Florida.
