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Hot water tips, from the tank to the tap

Image of kids washing dishes
After space heating, hot water tends to use the most energy in the home. Setting the hot water temperature can be a tricky thing as you try to find to find the balance between efficiency, safety, and practicality.

Save on hot water heating while ensuring safety and efficiency in the home

For most of us, water heating is one of the biggest energy users in your home. So it makes sense to ensure you're being as efficient as possible with your hot water heater, and making smart choices around your hot water use, so that you can find savings throughout the year.

Too hot and you run the risk of scalding at the tap and wasted energy for heating that water. Not warm enough, and you'll struggle to wash your soiled hands or that dirty pan – and hygiene could become an issue.

We've consulted BC Hydro engineer Gary Hamer for a list of things you should know to ensure both hot water efficiency and safety:

1. Temperature at the tank (60°C) and tap (49°C) are two different things

The BC Plumbing Code notes that hot water delivered at 60°C will severely burn human skin in one to five seconds, while at 49°C, the time for a full-thickness scald burn to occur is 10 minutes. Children, elderly and persons with disabilities are particularly at risk of scald burns.

So while it might seem reasonable to turn down the tank temperature, doing so can reduce the effectiveness of the hot water system from two perspectives: availability of hot water, and danger of bacterial growth. But don't worry. The Plumbing Code's got you covered, requiring that water be stored at 60°C in the tank as a precaution against bacterial growth, and delivered from the tap no higher than 49°C to prevent scalding. This is done by using a mixing valve to temper the delivered-water temperature at taps, bathtubs and shower heads. Such mixing valves can either be located at the faucet or within the water supply system.

If you're concerned that children or elders might be scalded at a sink faucet, teach them to turn the cold water on before the hot, or modify your plumbing when renovating. The Canada Safety Council recommends that if the water coming out of your tap is too hot, you can install valves in the plumbing lines to reduce the temperature of the water delivered at the tap by mixing in cooler water.

Another option is to install anti-scald devices at individual taps; they slow the water to a trickle if it gets too hot.

2. Favour showers over baths, and limit them to five minutes

There's no easier way to save on hot water-related energy costs than to choose showers over baths, as a bath can use three to six times as much hot water as a five-minute shower. But shower length is the key. If two people in your home cut their shower time by a minute each, you could save $30 on energy costs over a year. Cut showers by two minutes, and you could save $60.

3. Fix that leaky tap

It's easy to put off fixing a leaky tap, but that steady drip adds up. Fixing a hot water leak in your faucet can save up to $9 per year in energy costs.

Here's how to fix that leak.

4. Wash clothes in cold water

By switching from hot to cold water for an average of three loads per week, you could save up to $22 per year on your energy bill.

5. Turn off the tap while brushing teeth, shaving

A couple good things happen when you turn off the tap while brushing your teeth. One, you save water. Two, you're more likely to actually brush more carefully and longer than you would if you left the water running. This can work wonders with reluctant kids and teens. Ditto for those who are shaving. Fill part of the sink with hot water instead of letting the water run, and take the time to fix your sink stopper if it's leaky, as you won't need to keep refilling the sink.

6. Wash as many dishes as possible in the dishwasher

It can be therapeutic to do the dishes, but other than big pots that don't fit in the dishwasher (and pans that require scrubbing), let the dishwasher do the work instead. Handwashing dishes uses more water.

7. Right-size your hot water tank

You'll waste energy with a 60-gallon tank if a 40-gallon tank is enough to meet your household needs. Just be careful to avoid going so small in the name of efficiency that you drain your tank regularly and damage your tank through "thermal shock", caused by expansion and contraction of your tank when it's refilled with cold water too often. "If your tank goes through those cycles a lot, it's going to fail early," says BC Hydro's Hamer, whose family once rented a home in which the hot water tank failed twice in three years. "if you find you're draining your tank, you need a bigger size tank."

8. Electric? Gas? Consider a heat pump hot water heater

If it's time to replace your hot water tank, or you're building a new home and trying to decide which type to get, there are a few factors to consider. The size of your home, number of occupants and your typical water use are important in deciding which tank type and size are right for you.

Storage tanks are the most common type in Canada and come in gas or electric models. Have a chat with your heating contractor about the practicalities, and the pros and cons, of going with electric vs. gas, storage tank or tankless. And consider using BC Hydro's home renovation rebate of up to $1,000 for the purchase and installation of an electric heat pump hot water heater. Unlike heat pump space heaters, heat pump hot water heaters aren't weather dependent, and can be used effectively in any part of B.C.

9. Tankless heaters work best in smaller applications

You might find tankless electric options on the shelf in a big box store. Just be aware that the amount of power that large units require can put a strain on your electric service, the volume of electricity flowing into your home, measured in amperes, and which can be much lower in older homes. It can also put strain on the electric system in your neighbourhood and beyond. For that reason, BC Hydro's electric tariff (terms and conditions of service) prohibits large electric water heaters that don't have some storage capacity. While you've likely seen them under the sink in some office kitchens, you shouldn't consider them for your whole-home requirements.

Natural gas tankless options can provide whole-home solutions – with careful planning. ENERGY STAR® versions are much more efficient than a standard natural gas storage tank, but the suitability of this "on-demand" water heater will depend on how much hot water is needed for the home's peak requirements. For example, will the heater provide enough hot water for two showers to operate at the same time? Tankless water heaters can work well for cabins and smaller homes in particular.

FortisBC offers rebates on qualifying tankless water heaters, and has excellent information on the pros and cons of going tankless. Note that tankless models cost more up front than storage tanks and can have higher installation costs.