Updated September 18, 2026 · Aire One Peel Heating & Cooling, Mississauga
First question: do you own it or rent it?
Many Ontario homes have a rented water heater. If yours is rented, the rental agreement normally covers repairs and replacement, so call the rental company before you pay anyone else, and check the agreement to see what routine maintenance is included. If you own the water heater, everything below is yours to arrange. Not sure which makes sense for you? See renting or buying a water heater.
The maintenance checklist: tank and tankless
| Task | Tank water heater | Tankless water heater | How often | Who does it |
|---|---|---|---|---|
| Look for leaks and corrosion | Base of the tank, fittings, drain valve and the pan | Fittings, service valves and the condensate line | Monthly | You |
| Flush out sediment or scale | Drain the tank until the water runs clear | Descale the heat exchanger through the service valves | Yearly; more often with hard water | You for a tank; a technician for most tankless units |
| Test the temperature and pressure relief valve | Lift the lever briefly; water should flow, then stop | Test the pressure relief valve the same way | Yearly | You, carefully; the water is hot |
| Check the anode rod | Replace it when it is heavily corroded | Not applicable | Every 2 to 3 years | A technician, or a confident do-it-yourselfer |
| Confirm the temperature | 60 °C at the tank with a mixing valve limiting taps to 49 °C | Set point as the manufacturer recommends | Yearly | You |
| Clean the screens | Not applicable | Cold water inlet filter and air intake screen | Every 6 to 12 months | You |
| Inspect the venting and combustion air (gas) | Vent connection secure, no rust streaks or scorch marks | Vent and intake pipes clear and sloped correctly | Yearly | Licensed gas technician |
How to flush a tank water heater
Sediment settles at the bottom of the tank, insulates the water from the burner or the lower element and produces the rumbling or popping you may hear as it heats. Flushing it out once a year keeps the tank efficient and quiet.
- Turn a gas water heater to its pilot or vacation setting. Switch an electric one off at the breaker.
- Close the cold water supply valve at the top of the tank.
- Connect a garden hose to the drain valve and run it to a floor drain.
- Open a hot tap somewhere in the house so air can enter, then open the drain valve. The water is hot, so keep children and pets away.
- Let the tank drain until the water runs clear. Open the cold supply for a few seconds at a time to stir up what is left.
- Close the drain valve, open the cold supply and let the tank fill completely, until the open hot tap runs without sputtering.
- Only then turn the gas control back up or the breaker back on. An electric element that heats in an empty tank burns out within seconds.
One caution: on a tank that is eight to ten years old and has never been flushed, the drain valve can clog or fail to close again. In that case leave it, or have a technician do the flush.
Test the temperature and pressure relief valve
The relief valve is the safety device that opens if the temperature or the pressure in the tank climbs too high. Once a year, lift its lever for a few seconds: hot water should flow out of the discharge pipe and stop completely when you let go. If nothing comes out, or the valve keeps dripping afterwards, have it replaced. Never cap or plug the discharge pipe.
Check the anode rod
The anode rod is a sacrificial metal rod that corrodes so the steel tank does not. It is the main reason one tank lasts eight years and another lasts twelve. Have it checked every two to three years and replaced when most of the metal is gone or the steel core wire shows. The rod threads into the top of the tank and needs a large socket and headroom above the heater, so most homeowners leave this one to a technician.
Set the temperature: 60 °C at the tank, 49 °C at the tap
The Government of Canada advises setting the water heater to 60 °C (140 °F) to prevent the growth of harmful bacteria such as Legionella. Water that hot can scald, so the same guidance calls for mixing valves set to 49 °C (120 °F): automatic mixing valves on faucets, showers and tubs, or an anti-scald mixing valve on the water heater. Turning the tank itself down to save energy is not a safe trade.
Tankless water heater maintenance
A tankless unit has no tank to flush, but scale builds up inside its heat exchanger and cuts both flow and efficiency. About once a year the heater is isolated with its service valves and a descaling solution is circulated through the heat exchanger with a small pump, following the manufacturer’s instructions. Our tankless versus tank cost comparison lists what a descaling visit costs. Between visits, clean the cold water inlet filter and the air intake screen every 6 to 12 months. Maintenance records also matter for warranty claims; see our Navien tankless warranty guide and these tankless maintenance tips.
Warning signs: when to stop and call
- Water around the base of the tank. A leaking tank cannot be repaired and needs replacing.
- Rusty or discoloured hot water, or a rotten-egg smell: usually the anode rod or the inside of the tank.
- Rumbling, popping or banging that a flush does not cure.
- A relief valve that drips or discharges on its own.
- A pilot that will not stay lit, an error code on a tankless unit, or not enough hot water: start with our no hot water checks.
- A smell of gas. Leave the house and call your gas utility’s emergency line from outside.
A tank water heater has a rated life of about 8 to 12 years and a tankless unit about 20. Near the end of that life, compare repair with replacement on our water heater repair page, or see the options for a hot water tank or a tankless water heater.
Frequently asked questions
How often should a water heater be flushed?
Once a year is the usual schedule for a tank water heater, and more often if your water is hard or the tank rumbles or pops as it heats. A tankless water heater should have its heat exchanger descaled about once a year, following the manufacturer’s instructions.
What temperature should a water heater be set to in Canada?
The Government of Canada advises setting the water heater to 60 °C (140 °F) to prevent the growth of harmful bacteria such as Legionella, and using mixing valves set to 49 °C (120 °F) so the water at the tap does not scald.
How do I know if the anode rod needs replacing?
The anode rod is a sacrificial metal rod that corrodes so the steel tank does not. Have it checked every two to three years. It needs replacing when most of the metal is gone, the steel core wire is exposed or it is coated in hard scale. Rusty hot water or a rotten-egg smell can also point to a spent rod.
Do tankless water heaters need maintenance?
Yes. Scale builds up inside the heat exchanger and reduces flow and efficiency. Clean the cold water inlet filter and the air intake screen every 6 to 12 months and have the heat exchanger descaled about once a year. Skipped maintenance is also a common reason for a denied warranty claim.
Who maintains a rental water heater in Ontario?
If your water heater is rented, the rental agreement normally covers repairs and replacement, so call the rental company before you pay anyone else. Check the agreement to see what routine maintenance, such as flushing, is included. If you own the water heater, maintenance and repairs are yours to arrange.
Prefer to have it done for you? Call Aire One Peel at 905-564-8545, see our water heaters page or ask about our protection plans.