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Can The Water Useage Regs Really Be This Difficult To Understand?


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#1 wittenham

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Posted 18 April 2016 - 10:34 AM

It has been a while since I updated. We moved in c18 months ago mostly because sleeping in the yurt meant very early dawns as the birds got going... We slowly ticked off the BC requirements, but one that has us confused is water useage. As relayed to us, our house can never pass, despite all low useage appliances and the like, because the calculator has no per person element to it. We have four toilets, three showers one bathtub and three people... for obvious reasons, all 7 of those appliances are not used simultaneously.

Does anyone know if it is correct that the water useage calc is simply a total of the appliances? If so, how does any house larger than medium size pass?

#2 PeterW

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Posted 18 April 2016 - 12:32 PM

You need to use the calculator - it gives the normalisation and other factors.

http://www.thewaterc...calculator2.asp

I've done a quick pass - I used dual flush, reasonable taps and showers etc and came out at 123 litres per day so within regs

#3 bitpipe

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Posted 19 April 2016 - 09:44 AM

Hi, from memory of doing this for the initial BR submission, your allowance is 125l per person per day.

You also get a credit for rainwater harvesting - we are installing a very basic system (4 1000l IBCs, garden use only) to achieve this, might be an option to get past BR?

Alternatively buy some low flowrate taps if you need to 'downgrade' to pass and then replace.

#4 jsharris

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Posted 19 April 2016 - 09:53 AM

Drill a borehole. Exempts you from all the water regs bits of the building regs in one go................................... :)

#5 mrpunter

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Posted 19 April 2016 - 10:29 AM

It makes no difference how many WCs you have, just their cistern sizes. Shower flow rates and bath capacity is also a big factor, but it doesn't matter how many are in the property.

#6 bitpipe

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Posted 19 April 2016 - 05:54 PM

Taking a closer look at the worksheet, it averages out the consumption for each type of usage and then applies typical per person usage.

Question is when & how is this confirmed for BR?

We submitted an initial water calc when we were at the drawings approval stage of inspection (we're using an independent BC), will they check that I installed the exact shower and cistern types? If so, how?

#7 wittenham

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Posted 19 April 2016 - 07:46 PM

thanks all, and it is not clear to me how the per person element is calculated. Can anyone shed light on this? There does not seem to be fields in the calculator for number of people in the house/number of bedrooms, etc?

#8 bitpipe

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Posted 19 April 2016 - 08:19 PM

View Postwittenham, on 19 April 2016 - 07:46 PM, said:

thanks all, and it is not clear to me how the per person element is calculated. Can anyone shed light on this? There does not seem to be fields in the calculator for number of people in the house/number of bedrooms, etc?

It doesn't, it averages the shower flow, bath volume, flush volume etc.. and has typical per person usage values hardcoded - It's effectively calculating the use for just one person. I.e. if you have 4 loos and they're all 3.99l per flush (which is what my Gebrit dual flush gives) then it will just take 3.99l as the per flush volume. If you have one 15 and one 25l/s shower then it will average to 20l/s etc..

Your issue is not the number of toilets, its their flow rate - likely the showers are the culprit. Did you have to prove what you installed?

How much are you over? Any scope to fit flow restrictions to the worst culprits?

#9 bitpipe

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Posted 20 April 2016 - 01:46 PM

Had a chat with our plumbers today - they're surprised that it's an issue as in their experience few BCs check the flow rates post completion.

However, their recommendation is to install flow restrictors on showers and sink / kitchen / utility taps to get you back on target. When you're signed off you can remove them.

Your Gebrit dual flush cisterns should already be pretty efficient and water softeners, dishwashers & washing machines are fixed assumptions in the tool (unless you have ultra low usage versions in which case you may be able to claw back some credit).

They said that once they were asked to put flow restrictors on bath taps, which makes no sense as baths are measured by volume, not flow.

#10 wittenham

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Posted 20 April 2016 - 05:16 PM

Thanks bitpipe, and I need to look more closely at this to understand why we seem to have such odd figures. We have a manifold system that would let us dial back volume if anyone came to measure, but they are just going off the calcs we have done.

#11 PeterW

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Posted 20 April 2016 - 05:28 PM

If you use the link in the post above you can put in all the taps you have etc. by brand and model.

Look at where your bigger figures come out on the right hand column and work on that.

The only real places you can make a difference are taps and showers so concentrate on those first.

If needed, post up what you have and someone may be able to help you

#12 bitpipe

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Posted 20 April 2016 - 05:56 PM

You can also manually enter the flow rates (by ticking the black box on the right or each row) if your particular model is not there - if you check the technical specs on MegaBad or Reuters for items you'll usually find the flow rate there.