Simple measures to reduce consumption can help lower bills, conserve water and result in lower annual bills, according to Irish Water.
The survey by the network operator shows that average consumption stands at 150 litres per day per person – the equivalent of two bath tubs – but much of this is wasted.
Overfilling kettles, taking long showers and not filling washing machines are the most common wasteful practices, with the survey showing that 81pc of 2,000 respondents do not know how much water they use on a daily basis.
The research was published as part of a public information campaign to inform customers about the value of water and the benefits of making simple changes. It says that each person consumes some 150 litres of water per day, or 54,750 litres of water per year, much of which is flushed away.
Water charges will be introduced from autumn this year with the first bills expected to land through letter boxes in January 2015.
While the costs have yet to be decided by the Commission for Energy Regulation, which will regulate the sector, the price per 1,000 litres of water currently paid by commercial customers to local authorities range from €1.59 in Kildare to €3.03 in Wicklow, according to employers' group Ibec.
Using the average of €2.37, the figures show that average annual water bills per person will be €129.75, but that does not include the free allowance promised by the government.
But making changes will help reduce the average bill.
Showers are one of the biggest consumers of water, with the average seven-minute shower using 49 litres, with power showers using up to 175 litres.
The survey shows that two in every three homes have a power shower, using 63,800 litres a year per user. Reducing your shower time by just one minute could save up to 9,000 litres of water per year – leaving you with €21.33 more in your wallet.
Brushing your teeth with the tap running is one of the most common ways of wasting water, with six litres of water used per minute. By turning off the tap when brushing your teeth, it is estimated that up to 7,000 litres of water can be saved per year – yielding a saving of €16.59.
In all, immediate savings of €37.92 can be made – reducing annual bills per person by almost 30pc.
"It's clear from the findings that many of us are unaware of the sheer volume of water we are using on a daily basis," Elizabeth Arnett from Irish Water said. "It also confirms that there are many opportunities for us to reduce water wastage. Understanding how much water we use will help us determine how much we can save.
"In advance of water charges being introduced, there are simple steps people can take to make a big difference to the amount they use."
The survey also shows that 81pc of respondents underestimate how much water an average washing machine or dishwasher uses per load.
However, 90pc said they fully load the washing machine, which helps to conserve water and save money by reducing energy bills.
Two-thirds of those surveyed also said they tended to overfill kettles, while 28pc with a garden had never heard of a water butt, or a container for collecting rainwater from the roof and downpipes which can be used for watering plants or washing the car.
10 Simple Top Tips for reducing your Water Bill
Keep a jug of water in the fridge
Use a basin to rinse or clean your fruit and vegetables
Use a bucket of water, not a hose
Use smaller cisterns in the toilet
Be leak free
Only run your washing machine and dishwasher when full
Don’t leave the tap running when brushing your teeth
Reduce your shower time
Know how to turn off your water supply
Put enough water in your kettle for your cup of tea or coffee, don’t fill it up