Water New Zealand Web Forum

[Bryan Bates]

What guidelines or references are Councils using for determining what is "reasonable" household water use?
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Cirrus Associates Ltd

[normb]

I have measured actual water use in urban communities on and off for many years. Individual water use does not appear to have changed over a very long period - 40 years at least in my experience. The figure I have used is 190 Lpcd (litres per capita day) as being fairly accurate - so much so that I have used it predictively to ascertain “normal” use when users have made enquiry as to what to them has seemed an abnormally high account. The figure is reliable for children including babies. The only group that falls outside this norm is the elderly, when the figure can drop to around 140 Lpcd, sometimes even less - perhaps the elderly don’t wash It is also useful for gauging “normal” sewer discharge, taking the figure of 80% of water usage going to waste. However, I am unsure how accurate the 80% figure is.

On a very few occasions only I have discovered families where the 190 Lpcd criteria has failed - these being those that have applied water savings to a ridiculous level, bordering on unhygienic - but such is very infrequent.

I suspect the figure of 190 Lpcd may not apply however to other than reticulated supply.

cheers

[Rob]

Rob Blakemore and Steve Burton did a really good paper on water demand for the NZWWA Conference in 2007. Title was 'An assessment of peak daily demand in Tauranga city and implications for water supply management'.

[wernerg]

Hi,

NZS 4404, 2004 as a national standard quotes between 180l/s to 250l/s.
Peak Factor PF=2.5 Infiltration Factor IF = 2; Number of people per dwelling = 2.5 to 3.5. Actual HEU is 2.6 people/dwelling (Statistics NZ).

However the demand drops when water meters are introduced.
Councils are more and more adopting NZS4404, 2004 as I can see.
We are currently writing a COP implementing NZS 4404

Water supply for irrigation needs to be added to the above figures, which actually cranks up the final demand to higher levels.
To my understanding water reuse should be more encouraged as most Kiwis take a constant water supply for granted and this will change in some areas of the country. In general the awareness of how precious water will become in the future is still very low in NZ and at this stage I can't see much of a change here.

Regards Werner Gebauer

[Dylan Stuijt]

NZS 4404 is a reasonably good guide if you live in Auckland or anywhere on the west coast of NZ where you have fairly regular rainfall through out the year.

On the East Coast of NZ, the recommended figures are very much on the low side. The biggest difference being irrigation or discretionary water use as mentioned above. Our winter figure averages around 250ltr/p/day. However this can over double and even triple during a very hot summer. Whether this is "reasonable" is open to debate. If it’s competing with horticultural or business thats dependant on water, then I would say it probably is unreasonable, but not necessarily inefficient.

I'd be weary of quoted household metered figures, as they often only include what goes past the boundary and don't include, operational usage, mains flushing/scouring, hydrant testing, tanker filling, leakage, etc.. but if this is what your after, there's plenty of meter data available around.

Our residential average is 420ltr/person/day (1,100 Ltr/property/day) which includes all operational usage. Our winter usage drops to below 200 Ltr/person/day. Lifestyle blocks can get as high as 3,000 - 5,000 ltr/property/day during summer (each household individually metered).
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Water Supply Manager - Hastings District Council

[amyryan82]

I recently did a survey on 18 Tauranga households from June - Oct 09 and the average use per household was 430 l/conn/d

[normb]

[quote="amyryan82"]I recently did a survey on 18 Tauranga households from June - Oct 09 and the average use per household was 430 l/conn/d[/quote]

With respect, the number you have obtained is of limited value without some knowledge of the numbers of people per household. Alternatively, I would gauge that the number is 2.26 persons/household in your survey. Am I close ??

cheers

[Wicca]

Greetings,
We work on a straight 600 litres/day/domestic connection . . . this is based on 150 litres/person/day.

Not scientific but works well for most of our calculations

Cheers
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The earth is the insane asylum for the universe