Hot water tank FAQ

Cold water enters through a dip tube to the bottom of an insulated tank, a gas burner or electric elements heat it, and hot water leaves from the top when a tap opens. A thermostat controls the temperature. See how a hot water tank works.

Yes. It is connected to the cold water supply, so the water inside is at house pressure. That is why every tank has a temperature and pressure relief valve.

A gas tank has a vent pipe on top and a gas line with a valve near the bottom. An electric tank has no vent, an electrical cable into a box on top, and two small covers on the side for the elements.

The T&P valve exists to prevent that by releasing water before temperature or pressure becomes dangerous. Never cap, plug or disable it, and have a dripping valve investigated.

Many atmospheric gas tanks with a standing pilot and a thermopile-powered control keep heating in an outage. Electric, heat pump, power-vent and most tankless units need electricity.

Both trades work on them. The water connections are plumbing; gas lines and venting need a licensed gas fitter, and some HVAC contractors hold that licence. Check who is authorized in your province.

Public health guidance in Canada is 60 °C at the tank to limit Legionella, with mixing valves delivering about 49 °C at faucets, showers and tubs to limit scalds. See temperature setting.

Storing water at 60 °C helps control Legionella. The National Plumbing Code 2015 requires electric storage tanks to be set at 60 °C because stratification can leave the bottom cooler.

Size by your busiest hour. Three showers and a dishwasher in one hour is about 152 litres, which a typical 40-gallon tank covers. Use the size calculator.

Gas recovers faster and usually costs less to run where gas is cheap; electric is simpler to install and has no combustion risk. A heat pump model can beat both on running cost. See gas vs electric.

It can be for space savings and long showers, but cold winter inlet water raises the power needed: two showers at once from 7 °C water need about 44.5 kW. See tankless vs tank.

It cannot run out the way a tank does, but if too many fixtures run at once for its capacity, the water will not reach the set temperature.

They work well indoors in a basement or utility room that stays reasonably warm. They cool the room they sit in and rely more on their electric elements in cold spaces. See heat pump water heaters.

Yes. It moves heat from the surrounding air into the water, so the room gets cooler and drier. That helps in summer and adds to space heating demand in winter.

A gas tank with a fan that pushes exhaust through plastic pipe, usually out a side wall, so it does not need a chimney. It needs an electrical outlet. See power vent vs direct vent.

You need one where a check valve, backflow preventer or pressure-reducing valve closes your system, because heated water has nowhere to expand. Many codes and municipalities require one then; confirm locally. See expansion tanks.

As editorial planning ranges, gas tanks 8 to 12 years, electric and heat pump tanks 10 to 15, tankless units 15 to 20. Hard water shortens life; flushing and anode replacement can extend it. See how long tanks last.

Common sources are the drain valve, water from the T&P discharge running down, condensation, or the tank body itself. A tank-body leak means replacement. See tank leaking.

Usually a loose or corroded fitting on the hot or cold line, the anode port or the T&P valve. These are often repairable.

A small drip from a fitting can wait for a scheduled repair. Water from the tank body, water near electrical parts, or a fast leak needs you to shut the cold supply and the gas or power now.

Shut the cold supply valve above the tank, turn off the gas or the breaker, keep away from wet electrical equipment, and find where the water is coming from before calling for repair or replacement.

Usually high water pressure or thermal expansion in a closed system, debris on the valve seat, or a worn valve. Never cap it. See T&P valve dripping.

Common causes are a weak thermocouple, a dirty pilot, a tripped flammable-vapour sensor, drafts or backdraft, or a gas supply problem. See pilot light won't stay lit.

Sediment on the tank floor traps water that flashes to steam when the burner fires. Flushing may help on a tank that has been maintained. See rumbling and popping.

Usually sulphate-reducing bacteria react with a magnesium anode to produce hydrogen sulphide. If only the hot water smells, the tank is the likely source. See rotten-egg smell.

A gas water heater can if combustion or venting goes wrong. Install certified CO alarms, keep vents clear, and have fuel-burning appliances inspected at least yearly or as the manufacturer directs.

Yes. Snow or frost over a power-vent or direct-vent terminal can trip the heater's safety switch. Health Canada advises checking exhaust vents during and after snowstorms.

Yes, as the manufacturer recommends, typically about once a year, to remove sediment. On an old, never-flushed tank, flushing can disturb heavy sediment and make a worn drain valve leak. See how to flush a tank.

Yes, eventually. Inspect every few years, sooner on softened or hard water, and replace before the steel core wire is exposed along most of the rod. See anode rods.

Electric work and plumbing may be allowed with permits in some places; gas work usually requires a licensed gas fitter. Rules are provincial. See can I replace my own water heater.

As a 2026 planning estimate, a like-for-like 40- to 50-gallon gas tank typically plans at $1,800 to $3,200 installed and an electric tank at $1,400 to $2,600, before add-ons. See the cost guide.

Renting avoids the purchase price and usually covers repairs, but fees continue and often rise. Over a tank's life, buying often costs less. Run your numbers in the Rent or Buy Calculator.

Read your agreement for the buyout schedule, removal or return fees and notice process, then ask the provider in writing for the buyout amount before booking a replacement.

Many policies cover sudden water damage, subject to terms and deductibles, but not the worn-out tank itself. Check your policy wording or ask your broker.