What to Expect When Replacing a Water Heater—And How to Avoid Getting Rushed or Overcharged

Waking up to a cold shower is frustrating. Finding out your water heater has finally given out? Even worse. The good news: when you call a qualified plumber, replacing it doesn’t have to be chaotic or confusing.

But most homeowners have no idea what actually happens during a water heater replacement. Is it messy? Will your home be without water all day? What should you be prepared for?

This guide walks you through the real process – what the plumber does, how long it takes, and what to expect from start to finish.

Step 1: Confirming the Replacement Is Necessary

Before removing anything, a licensed plumber should confirm that a replacement is truly needed. Some issues can be repaired, but others mean the system is done.

A few clear signs your water heater is beyond repair:

• Water leaking from the bottom of the tank
• Rust in the hot water
• Strange noises like popping or banging
• Heating element failure on older units
• The unit is 10 years old or more

If any of these apply, your water heater replacement should be scheduled immediately. A failed tank can cause water damage, mold, and disruption to your home.

Step 2: Turning Off Power, Gas, and Water

For safety, all utilities connected to the unit must be shut off before removal begins.

• Electric water heaters need to be powered down at the breaker
• Gas water heaters must have the gas shut off and the pilot light extinguished
• The cold water supply is turned off and pressure is relieved through a nearby tap

This step prevents burns, flooding, and other safety risks during disconnection.

Step 3: Draining and Removing the Old Water Heater

Once everything is off, the tank is drained using a garden hose connected to the drain valve. This can take 20 to 45 minutes depending on the size of the tank.

When fully drained, the plumber will disconnect the water lines, gas or electrical connections, and remove the tank from its position. This is a good time to assess the condition of nearby pipes, fittings, and valves.

In older homes, parts like expansion tanks, shut-off valves, or gas lines may need updating to meet current plumbing code.

Step 4: Preparing the Space for the New System

This step is often overlooked by rushed installers. But it’s critical.

The plumber should check:

• That the venting system is intact and suitable for the new unit
• Whether the water supply lines need to be cleaned or replaced
• If there is a proper drain pan in place (especially in attics or finished spaces)
• If new pressure relief valves, unions, or expansion tanks are required by code

Skipping these checks can lead to premature failure, insurance issues, or safety risks.

Step 5: Installing the New Water Heater

Once prep is done, the new unit is carefully moved in, leveled, and secured. Connections are made to both the water supply and either the gas or electric source. The plumber fills the tank slowly to reduce air pockets and potential hammering in the lines.

Key things a proper install includes:

• Leak testing at every connection
• Verification of correct water temperature settings
• Checking the vent draw (for gas models)
• Ensuring the unit is registered for warranty

The first full tank of hot water may take 30 to 60 minutes to heat up.

Step 6: Clean-Up and Walkthrough

A professional job doesn’t end when the tank is hot. The area should be cleaned, the old tank removed, and the customer walked through the new system.

A good plumber will explain:

• Where the shut-offs are located
• How to check the temperature and pressure settings
• How often the tank should be flushed
• What to do if you notice leaks, drips, or changes in performance

This step is especially important for homeowners who just moved in or have never dealt with a new system before.

What to Expect on Timing

A straightforward water heater replacement usually takes between 2 and 4 hours from start to finish. If your home needs additional code updates or the old unit is in a tight location, the job may take longer.

If you’re switching from a standard tank to a tankless model, expect a longer timeline and possible modifications to your gas line, electrical system, or venting.

Replacing the Heater Is Only Half the Job

Getting hot water back is the obvious goal. But how the system is replaced matters just as much. A rushed or careless job can lead to leaks, short equipment life, and wasted energy.

At Rockwater Plumbing, we take the time to do replacements properly. That means checking every connection, replacing outdated parts, and making sure the new system matches your home’s actual usage—not just what was there before.

If your water heater has failed or is showing signs of wear, get in touch. We’ll inspect it, walk you through real options, and get it replaced safely, efficiently, and without cutting corners.