New build water calcs - I don't get it

[dysty42]

So I'm nearly finished a new build and the only bit of paperwork that is outstanding is the water calcs. I did have some earlier from the epc people but a fair bit has changed.. and I now know exactly what is installed.

I see there are several online calculators. So have tried to put data in, at least for the items I can actually find any water usage data for(and have made up stuff for those I can't).

But it seems to be based on just 'you have 3 toilets so you'll use this much', but surely this is entirely meaningless without some context on the size of the dwelling(which doesn't seem to be factored in in any way).

Eg a 1bed house with 3 bathrooms is not likely to use more water than a 5 bed house with 1 bathroom.. is it?
And is it not likely that a house with a dishwasher will use _less_ water overall than one without, if it is used efficiently?
Does the max flow rate of a tap really matter at all, as who really turns a tap on full blast?
I would be fairly surprised if I use over 100 litres of water a day personally.

To me, how much water gets used is not really anything to do with the max capacity to use water, but really just how people use water.

How long until they introduce water flow tests?

Am I going mad, or did anyone else see this as a load of nonsence?

[Mr Punter]

I don't believe you need the calculator, just a written statement saying "I confirm that water consumption is calculated at less than 125 litres/person/day using fittings
approach”.

[Bramco]

50 minutes ago, dysty42 said:

Am I going mad, or did anyone else see this as a load of nonsence?

 

Agreed - not that you're going mad of course - but the calculators take no account of the number of people. We have to do the 110l/per person limit but if you add up all the toilets, showers, a bath, washing machine etc in the calculator then it comes out as way above 110l.

 

Where on earth does the per person bit get factored in?

 

Simon

[Mr Punter]

17 minutes ago, Bramco said:

Where on earth does the per person bit get factored in?

 

Because a person will only use on loo at a time, so consumption is not altered by the number of loos, just their efficiency.  They will take an average efficiency if there is more than one.

[Mr Punter]

I think it is accepted that these regs are a bit silly and not really what building regs are about (Health and Safety) which this bit has become self cert.  I heard recently that the new WC cisterns can often use more water than their old counterparts because people are unaware when there is a leak of water from the cistern into the pan.

[SuperJohnG]

9 minutes ago, Mr Punter said:

I heard recently that the new WC cisterns can often use more water than their old counterparts because people are unaware when there is a leak of water from the cistern into the pan.

That sounds like one of those tails of woe  where people don't like change. Youd hear it constantly running. Close coupled is much better. 

 

I assume this is for English regs? I havent seem this in Scotland. Albeit..we don't really have a water issue (well shortage anyways) ?

[Mr Punter]

2 minutes ago, SuperJohnG said:

That sounds like one of those tails of woe  where people don't like change. Youd hear it constantly running. Close coupled is much better. 

 

I assume this is for English regs? I havent seem this in Scotland. Albeit..we don't really have a water issue (well shortage anyways) ?

https://www.theguardian.com/environment/2020/sep/29/dual-flush-toilets-wasting-more-water-than-they-save

[Bramco]

32 minutes ago, Mr Punter said:

Because a person will only use on loo at a time, so consumption is not altered by the number of loos, just their efficiency.  They will take an average efficiency if there is more than one.

 

But the calculators work through how many showers, loos etc you have and there is nowhere to put in how many people there are......    I can only use one loo obvs but our new house will have 3 en-suites and according to the calculators we'll be massively over the 110l per person.

 

Simon

[Mr Punter]

 

23 minutes ago, Bramco said:

 

But the calculators work through how many showers, loos etc you have and there is nowhere to put in how many people there are......    I can only use one loo obvs but our new house will have 3 en-suites and according to the calculators we'll be massively over the 110l per person.

 

Simon

 

If you have a hundred 5l toilets and 1 person flushes once a day it is 5l per person per day.

 

If you have one 5l toilet and 80 people flush once a day it is 5l per person per day.

[SteamyTea]

2 hours ago, SuperJohnG said:

Albeit..we don't really have a water issue (well shortage anyways)

We have no shortage either, but the most expensive water in the country.

It is not the amount of rainfall, more the storage and treatment.

If you live in a very rainy area, and most of the towns are close to the coast, then waste and run off water treatment is very expensive.

 

I think the water targets are base don national averages i.e. average usage and average houses, then a bit taken off, and then 'weighted' for house types i.e. size.

I live on my own, but the identical house 4 doors away, there are 4 adults, next to that there is a family of four, then a family of 3, then a single, then me, then a family of 3.

Now you cannot have 2.6666 people, so that will be called 3.  So the water calculation are possibly based on 3 people in each house of my size and type.

[SuperJohnG]

3 hours ago, Mr Punter said:

https://www.theguardian.com/environment/2020/sep/29/dual-flush-toilets-wasting-more-water-than-they-save

Typical click bait by the looks of thing. 

 

No hard and fast evidence. Plus you can have old style toilets which are close coupled and could run all night, in fact any toilet can run all night. To blame it on dual flush doesn't make sense imo. 

 

52 minutes ago, SteamyTea said:

We have no shortage either, but the most expensive water in the country.

It is not the amount of rainfall, more the storage and treatment.

If you live in a very rainy area, and most of the towns are close to the coast, then waste and run off water treatment is very expensive.

 

I think the water targets are base don national averages i.e. average usage and average houses, then a bit taken off, and then 'weighted' for house types i.e. size.

I live on my own, but the identical house 4 doors away, there are 4 adults, next to that there is a family of four, then a family of 3, then a single, then me, then a family of 3.

Now you cannot have 2.6666 people, so that will be called 3.  So the water calculation are possibly based on 3 people in each house of my size and type.

Do you guys pay for how many liters you use? or standard no matter you use? we have a standard amount payable as part of council tax.  

[dysty42]

So far as I can see what I am calculating fundamentally takes no account of the ratio of people likely inhabiting the house(house size) vs the number of showers / taps / toilets present.

My house is a two bed, each with ensuites(and a downstairs wc). Based on the calcs, that produces far worse numbers than say a 2 bed with a family bathroom. But, the 1-4 inhabitants of the said two comparable 2 bed houses would likely use about the same amount of water in reality.

Excessive water usage is all about how people use things really.. the authorities would be far better spending their time educating people imho. Or simply ban stuff that uses a high amount of water like very powerful showers.

Meantime, how many water pipes in the UK are leaking? I reckon quite a few.. force the utilities to spend the money to repair their infrastructure, or face big fines.

[SteamyTea]

13 hours ago, SuperJohnG said:

Do you guys pay for how many liters you use?

Yes, and it is painful.

But it does keep the beaches clean for the dogs to shit on.