Hot water services

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What’s the right capacity for you?

There are three main types of hot water services (HWS): mains water, gravity feed and instantaneous.

The most common by far are the storage systems – they heat and store water in tanks. The three types are:

• Mains water (also known as "mains pressure"). Hot water is delivered at a similar pressure to your cold water. It means you can have more than one tap on at once without greatly affecting water pressure.
• Gravity feed (also known as "low pressure"). Pressure is created from a tank located in the roof. The pressure depends on the height at which it is located relative to the tap. It is common to find these in older buildings or homes that are not connected to mains water. Although not delivering the higher pressure of mains systems, gravity feed systems are usually cheaper and generally last longer.
• Instantaneous systems heat water only as required. There is a common misconception that all instantaneous heaters are gas models. In fact they can run on either gas or electricity. The major advantage is that they never run out of water. On the downside, running costs can be high. Smaller units can be used as a supplement to an under-capacity storage system. 

The storage tanks of hot water services are made from a variety of materials, including copper, glass enamel, lined steel or stainless steel. Warranties for tanks range from 5 to 15 years.

Popular storage systems come in sizes ranging from 80 to 400 litres. As a general guide a household of four people would require a HWS of 250 litre capacity. This should be adequate to cover all general use as well as a dishwasher and washing machine.

For more information:

Contact the Master Plumbers Association of Tasmania on 1800 667 766.