The majority of houses waste a great deal of water each day when people run taps waiting for them to run hot – for example in the kitchen, bathroom sink and shower. Some claim up to 10 percent or more of household water is wasted while you wait for the shower or taps to run hot.
If we look at the average water use in a Melbourne household, with an average of 200 litres per day per person during water restrictions, and an average Melbourne household having two to three people…. the water wasted waiting for taps to run hot could be 40 or 60 litres a day.
A three person Melbourne household wasting 60 litres per day this way is 22,000 litres per year.
Water usage + sewage disposal = $1.0248 / kl + $1.3392 / kl = $2.364 / kl * 22 kL = $52 per year down the drain. Also, the price of water is set to double over the next few years.
If 60 m² of your yard was gardens for growing fruit and vegetables, it would only require about 33,000 litres per year. This isn’t even taking into account grey water capture (bathroom and washing machine water) which could be 89,000 litres p.a. and/or rainwater harvesting off your roof.
Another important fact point is the greenhouse gas emissions associated with water use in Melbourne. The delivery of potable water in Melbourne means the equivalent of 0.173 tonnes of CO2 is emitted per mega litre (1 million litres). Wastewater in Melbourne is associated with the equivalent of 0.875 tonnes of CO2 emitted per megalitre.
Water wasted by running taps until they run hot is both potable and now wastewater, so the combined CO2 emissions associated with it is about 1 kg CO2 emitted per 1000 litres – all for water that was not used – the emissions were for nothing. If we look at a Melbourne household with three people, wasting 22,000 litres per year, we find that 22 kg of carbon dioxide (or if you prefer, 440 black balloons) is emitted per household each year just running taps to hot.