Friday, April 2, 2010

How to do a home water audit..

Thanks to all those that have commented on the household water audit we conducted in the beginning of February. Since publishing the post I have had many queries as to how I conducted the audit - so have decided to provide more information here.  I hope this post will inspire people to conduct their own home water audit.

Before you begin your water audit you will need to measure how much water different taps, showers and appliances use in your house. Here are some of the things I did.

Toilet - I measured how much water was used to flush the toilet by turning the tap to the toilet off, flushing the toilet and then I took the top off the cistern and with a jug, measured how much water it took to fill it for a half flush or a full flush.

Dishwasher and washing machine - I referred to the owners manual, if I could not find it at home I went online and found it (you will need a model number).  Remember that different cycles use different amounts of water - so make sure you record what cycle you used for each wash.

Shower - I put a large bucket under the shower and collected all the water from the shower for a minute.  I then used a litre jug to measure how many litres were used.  This gives you a shower volume in litres per minute.  If you time how long each shower goes for you will be able to work out the volume of water used for each shower (how long your shower was multiplied by litres per minute you shower uses).

timing the shower filling a bucket.. after 1 minute I measured how much water was in the bucket

Bath - I ran the tap into the bath as if I was filling the bath.  Like measuring for the shower, I timed the bath tap for 1 minute and then measured how much water was in the bucket.  This gives you the flow rate of the bath tap in litres per minute.  Next step is to time how long it takes to fill your bath top the usual level.  Now you can work out the volume in the bath by multiplying you tap flow rate by the number of minutes it took to fill the bath.

Sink and handbasin - to measure water usage in a sink or handbasin I placed a container in the sink (or handbasin) and recorded how many times it filled over the course of the week.  For e.g., in our kitchen sink we put a 6 litre plastic cake box and I simply rinsed wash rags, vegies, dishes etc over this basin and recorded how many times it filled for the week.

catching the water used for rinsing dishes etc in the kitchen sink

The next step is to set up recording sheets around the house.  For the week of our home water audit we had sheets up at various locations around the house recording things like:
  • the number of half and full flushes of the toilet
  • handbasin use for washing hands, cleaning teeth and shaving
  • how long each shower went for (yes I had a stop watch out)
  • how many containers filled in the kitchen sink and the handbasin
  • how many baths the kids had
  • number of times the dishwasher or washing machine were used as well as what cycle setting they were on
  • how many times we filled the dog buckets or chook water
  • a rough estimate of litres used for cooking and filling water bottles
  • if you use a sprinkler or bucket to water the garden from the an outside tap you will need to record this as well (we don't use town water on our garden at all) 

Our littlest filling in our toilet recording sheets

Here is a selection of our recording sheets we used for our water audit week - showing how basic the sheets were - nothing complicated

Just before you start recording your water usage for the week be sure to record your water meter reading.... if you record the meter reading at the end of your water audit week you can then check how accurate you were at measuring your water usage.  Orange City Council has a sheet on how to read your water meter

At the end of the week you can put all the information you have gathered into a table to analyse it a bit more... I just put it into a spreadsheet like Excel and you can play with the numbers a bit as well.

Here is our audit summarised.. you will see in the last column that the three biggest uses of water in our house were:
  1. the shower (44.1%)
  2. the washing machine (18.2%), and
  3. the toilets (16.3%)

How do your results compare to the average?

From you results you can work out what your avergae daily usage is per person - your weekly water usage divided by 7 then divided by the number of people in you household.  For e.g., our weekly usage was 3315 litres, which is a daily usage of 473 litres for 5 people.  This is is just under 95 litres per person per day.

You can also check you water audit results against you avergae daily usage from your latest water bill or old water bills.

I intend to do a water audit annually or every second year to monitor our consumption and identify new areas for better efficiencies.

I would be interested to hear about your water audit findings?


  1. what do we do when we get teenagers?

    btw - Orange city council allows us to recycle polystyrene

  2. Thanks for sharing such nice information about water audit.. keep writing..

    Anne Cole
    Water Efficiency Audit