The tank itself
Once the tank shell or its bottom seam is weeping, the heater is done. A dry, clean tank with one failed part is a repair, even on a heater that is not new.
The heater and the plumbing around it
Water Heater Repair and Replacement in Mesa and Phoenix
One Call Plumbing repairs and replaces water heaters in Mesa, Phoenix, and across the Valley. As plumbers, we look past the heater to the valves, pressure, relief line, and drains around it, because that is where many repeat failures start, and we quote the heater and the plumbing around it together.
Watch for these signs
Water heater trouble we get called for
- No hot water in the house or building, or only lukewarm
- Hot water that fades before a shower is over
- A wet garage floor, a full drain pan, or a ceiling stain under an attic heater
- Water running from the relief-valve pipe outside or into the pan
- Hot water at some fixtures and not at others
- Strong cold-water flow but weak hot-water flow
- A heater that knocks or pops as it heats, or a tankless unit that keeps shutting down
Our services
Water heater repairs and replacements we handle
- Gas and electric tank repairs, and tankless repair and descaling
- New shutoff valves and supply connectors at the heater
- Relief-valve replacement and discharge lines rerouted to drain where they should
- Drain pans and pan drains, including attic and upstairs installations
- Expansion tanks and house water-pressure checks when the relief valve keeps opening
- Replacement tank and tankless installation sized to real demand
- Commercial water heater repair and replacement
Your options
Repair or replace: what tips the decision
We price the repair first. These are the things that can make a new heater the better spend.
Your house water pressure
Pressure that runs too high, or a failed pressure-reducing valve, wears tanks and relief valves out early. A new heater on the same pressure ages the same way, so the pressure is fixed first either way.
The plumbing around the heater
Seized shutoffs, corroded connectors, a relief line that ends in the pan, or a pan with no drain all need correcting. When several are due on an older heater, doing them with a replacement costs less than doing them twice.
How the household has changed
A heater sized for two people may be the wrong one for five, or for a home with a new bathroom. If hot water runs short, a repair returns it to running short.
Around the Valley
Hard water works on more than the tank
Mesa and Phoenix both deliver hard water. Besides settling in tanks and scaling tankless heat exchangers, minerals stiffen the shutoff above the heater and can keep a relief valve from closing fully after it opens. Turning that shutoff now and then and having the relief valve checked when the heater is flushed catches both before an emergency.
Planning the work
What affects the price
- Whether the failure is a heater part or the plumbing around it
- Gas, electric, tank, tankless, or a commercial system
- The capacity and recovery a replacement needs
- Gas line, venting, circuit, relief-line, pan, and expansion-tank corrections
- An attic, rooftop, upstairs closet, or garage location, and the path out for the old heater
- Shutoffs, connectors, and piping replaced at the same time
When the heater is not the problem
Some hot-water complaints start in the pipes and valves, and a new heater will not fix them. We rule these out before quoting one:
- Hot water at the kitchen and one bathroom but not another: the heater is doing its job. The shower or tub valve is the usual cause, from a worn cartridge to a temperature limit set too low, and that is a fixture repair.
- Lukewarm water everywhere, even after a heater repair: a failed single-handle faucet or shower valve can let cold water cross into the hot line. With the heater's cold-water valve closed, a hot tap that keeps flowing points to that crossover.
- A newer tank that runs out quickly, with bits of white plastic in faucet aerators: the dip tube that carries cold water to the bottom of the tank has broken, so incoming cold water mixes straight into the hot outlet.
- A relief valve that drips after each heating cycle: heated water expands, and a pressure-reducing valve, check valve, or backflow preventer on the main leaves it nowhere to go. A correctly sized expansion tank stops it. Never cap or plug the relief pipe.
- Weak flow on the hot side only: scale and sediment can narrow the shutoff and fittings at the heater, or a supply connector can be kinked. Our low water pressure page covers flow problems on both sides.
Where water heater leaks end up
Emergency plumbing service for a leaking water heater is available 24/7 at 480-663-2255, including nights, weekends, and holidays, and the shutoff steps on our emergency plumbing page cover the heater's valve and the house main. Once the water is stopped, where the heater sits decides what to check:
- Attic and upstairs heaters: a full pan or a stain on the ceiling below means the pan's drain is missing, clogged, or too small, or the leak outran it.
- A shutoff above the heater that will not turn: older valves seize in hard water. Close the house main instead, and have that valve replaced with the repair.
- Water from the relief-valve pipe outside or in the garage: the valve is releasing pressure or heat, not the tank leaking. It still needs a diagnosis.
- Garage and slab floors: water spreading from a heater can wick under baseboards and into walls. Drying the area quickly limits the damage; drywall and flooring repair is separate from the plumbing work.
Tank or tankless: what changes in the plumbing
A tank of the same fuel usually reuses the existing water, gas or electrical, and vent connections, with worn pieces updated. A tankless unit mounts on a wall, so the hot and cold lines are rerouted to it, and it needs isolation valves on the water lines so it can be descaled, plus the gas, venting, condensate, or electrical work Water Heater Warehouse AZ's tankless page explains.
If the complaint is how long hot water takes to reach a far bathroom, that is the length of pipe, not the heater. A tankless unit in the same spot will not shorten the wait. Water Heater Warehouse AZ's chooser, linked below, compares the heater types side by side.
Sizing the replacement
A heater with the same gallons as the old one can still fall short if the household has changed. These answers are enough for us to size and quote the replacement:
- Who lives in the home or works in the building, and how many showers run one after another in the morning
- A large soaking tub, a multi-head shower, or anything else that draws a lot at once
- Whether the old heater ran out, and when
- Additions or bathroom remodels planned in the next few years
- For a business, the sinks, dish machines, laundry, or showers that all draw during the busiest stretch
What happens next
From the first call to hot water
- 1
Call or send the form with what the heater is doing and whether anything is wet. A photo of the heater and the pipes around it helps.
- 2
The technician checks the heater and the plumbing around it: the shutoff, connectors, relief line, pan drain, venting, and house water pressure.
- 3
You approve a price for the repair, or for the replacement and the corrections around it, before the work starts.
- 4
We test the heater and check each joint we touched before we leave.
Common questions
Water heater repair and replacement questions
Do you repair and replace water heaters in Mesa and Phoenix?
Yes. One Call Plumbing repairs and replaces gas and electric water heaters, both tank and tankless, at homes and businesses in Mesa, Phoenix, and the rest of the Valley, including commercial systems.
Can you fix or replace my water heater the same day?
Same-day water heater service is often available, depending on the job. Tell us the heater type, fuel, and what it is doing when you call or send the form. A heater that is actively leaking is an emergency, and emergency service is available 24/7.
Should I repair or replace my water heater?
Age, tank condition, the failed part, efficiency, parts availability, and the repair price all matter. A leaking tank needs replacement; many control and component failures can be repaired.
Do I need an expansion tank with my water heater?
If the main water line has a pressure-reducing valve, a check valve, or a backflow preventer, water that expands as it heats has nowhere to go, and an expansion tank gives it room. Without one, the relief valve often ends up doing that job. We check for these valves when we quote a replacement.
Why is water dripping from the pipe on the side of my water heater?
That pipe carries water from the temperature and pressure relief valve. A drip can mean high pressure, thermal expansion, an overheating heater, or a worn valve. It is a safety device, so have it checked rather than capping it.
Can you help size a commercial water heater?
Yes. Commercial sizing should account for peak-hour demand, recovery rate, redundancy, fuel or electrical capacity, and the cost of downtime.
Is tankless always more efficient or less expensive?
Equipment efficiency is only one part of the decision. Conversion cost, utility upgrades, usage, maintenance, recirculation, and expected service life should be compared for the actual property.
Related services
Related services and guides
Tank replacement budget
Planning a new tank water heater?
These ranges come from our past standard tank replacements, August 2025 to March 2026. Use them to plan; they are not a fixed offer.
- Standard tank replacement
- $1,750–$2,800
- 75-gallon tank replacement
- $3,000–$3,300
A replacement can run above these ranges. You get a written price for the whole job before any work starts.
What moves the price
- Tank size, and the model and warranty you pick
- Gas line, wiring, venting, or water-line corrections the old installation needs
- How hard the old heater is to reach and haul out, and the permit
We quote tankless, heat-pump, and commercial heaters on their own.
A photo of the model label and the pipes around the heater helps us quote.
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