Rainwater harvesting - How do you calculate 'pay off' period?

EricMears

OffGridLiving wrote: »

Does anyone know if water companies will make a fuss if they find out you are rainwater harvesting and you're connected to a mains sewer? Our sewage water bill is calculated on the amount of incoming water we use, so if we use 60 litres over the billing period, we're charged for the disposal of 60 litres of water into the sewers.

If our incoming water goes down to 30 litres because the other 30 litres is now coming from stored rainwater, our outgoing water will still be 60 litres but we will only be billed for 30 litres. I just can't see the water companies allowing that to continue, especially if RWH becomes more mainstream?

I don't know (it doesn't affect me) but really can't see why they should object.

Were I to receive any complaints on that score I'd be tempted to suggest that they might like to start metering sewage insted of guessing it.

OffGridLiving wrote: »

Just had another thought. As the OP has mentioned, you get a rebate if your rainwater goes to a soakaway or other water source rather than to a sewer. If you divert this into a rainwater tank and use it to flush the loo, then it's going back into the sewer system. Only the overflow from a full tank will now go into a stream. Again, I can't see the water companies allowing people to keep this rebate when most of their rainwater is going into the sewer.?

Our hearts bleed for the 'poor' water utility companies ! They've managed to maximise profits for years by charging most customers on a rateable value basis and continued to save money by not bothering to measure sewage.

I can see no way in which they could reasonably charge you extra for strictly obeying their own rules.

albyota

Hi,

We have a 4000L rainwater harvesting tank buried in the rear garden, used for flushing toilets, washing machine, and garden hose / car washing. I fitted it myself in 2004, I am billed by Anglian water and get £38 reduced off my bill.

From Anglian Water
"If you can show that none of the surface water from your property drains to the public sewerage system, either directly or through intermediate sewers or drains, you can reduce your sewerage standing charge by £38.00 per year.

We may charge some customers for the water they use but another company will charge for wastewater services. If this is the case, please contact the other company directly for details of their wastewater charges.

Charges for customers with meters
If you have a water meter, we base your charges on the amount of water you use, plus a standing charge.

Your sewerage charge is normally 90% of the water used as we allow 10% for activities like garden watering and car washing.

If you think that less than 90% of your water goes back to our sewer, please contact us."

See here http://www.anglianwater.co.uk/_assets/media/Surface-water-drainage-application.pdf

EricMears

albyota wrote: »

If you think that less than 90% of your water goes back to our sewer, please contact us.

See here http://www.anglianwater.co.uk/_assets/media/Surface-water-drainage-application.pdf

(I assume that albyota is quoting from an Anglian source rather than being an actual company rep )

Notice that Anglian aren't even asking customers to tell them if they think they might be putting more than 90% of the purchased water back into the sewer. Pretty sure that T&Cs from other water companies are very similar to Anglian's.

OffGridLiving

Eric, have you every thought about filtering your rainwater and using it for drinking water? I know the financials won't stack up for those who are on the mains, nor is it particularly sustainable having millions of individual filters rather than a large scale water purification system. For emergencies though, such as your reasoning behind having a header tank, being able to produce potable water from your rainwater reserves would be a real advantage.

EricMears

OffGridLiving wrote: »

Eric, have you ever thought about filtering your rainwater and using it for drinking water? I know the financials won't stack up for those who are on the mains, nor is it particularly sustainable having millions of individual filters rather than a large scale water purification system. For emergencies though, such as your reasoning behind having a header tank, being able to produce potable water from your rainwater reserves would be a real advantage.

You need to take a view on how much such a system would cost and how much benefit might be obtained from it. Treatment to potable standard isn't just a matter of filtration; you also need to kill off any bugs that might be present and both processes have to be done reliably (doesn't take a lot of contaminated water to make you very ill). I'd take a lot of convincing that such treatment is economically justified and efficient enough to be relied upon.

In the event of (extended) water mains failure, I guess we could boil some rainwater and use that for drinking but it would probably be just as easy to go to next village and fill a container from a friend's tap.

Many people filter their rainwater and use for washing machines etc. That's probably easier to justify on economic grounds. But it's also a matter of working out how much rain you can collect in a year and deciding if it will do all the jobs you need. In our case we've got around 90 sq m of roof and an average annual rainfall of around 800mm so I could expect to collect around 70 cu m of rainwater in a typical year - but that might be twice that amount in a very wet year or half that amount in a drier year. Nearly 40 cu m of that is needed for WCs so there could easily be years when we wouldn't collect enough water for washing. But the real killer is having a wife who doesn't really fancy the idea of washing in rainwater.


BTW, here is a link to a page discussing the charging structure for RWH related issues in a commercial environment. It may not be strictly relevant to domestic situations but I'd guess that the cost of introducing metering for sewage (or even rainwater) would far exceed any benefit water companies might expect to recoup.

Ken68

I did try, Offgrid, to filter rainwater using Britax equipment. Too slow and expensive and still doubts about residues. Ultra violet even more costly.
Have been a rainwater enthusiast for ten years now, would love a auto system but just can't make it happen.
Even more savings if I could use rainwater for the washing machine but have doubts on the filling mechanism. e.g. on a float or timed fill and then maybe the rainwater would need to be heated, say at least 60degrees.

Cardew

[QUOTE=EricMears;60573257



Our hearts bleed for the 'poor' water utility companies ! They've managed to maximise profits for years by charging most customers on a rateable value basis and continued to save money by not bothering to measure sewage.

I can see no way in which they could reasonably charge you extra for strictly obeying their own rules.[/QUOTE]

That I am afraid is simply incorrect and you apparently don't understand the finances of water companies.

Firstly charging on the basis of the Rateable Value(RV) of a property was mandated in the Water Act for properties built before April 1990.

The Government decided that compulsory metering would impose hardship on many families living in properties with a low RV. Occupants of pre-1990 properties could elect to have a meter fitted. They also have the choice to revert back to RV based charges within 12 months(24 with Anglian) if a meter is not advantageous. The meter is left in-situ and the next occupants should be metered.

Secondly as water companies have a monopoly, the Regulator(Ofwat) strictly controls the revenue and profit margins of all the companies.

Thus it makes no difference at all to the companies' bottom line(profit) if everyone is on RV charges, or everyone metered. They will just adjust their charges so their revenue is still the authorised £xBillion with a profit of £ymillion.

This is why water companies are not concerned if there is a reduction in their revenue from, say, Surface Water Drainage(SWD). If they collect in, say, £1 million less in SWD charges they simply are allowed to increase other charges to compensate. Put simply they are in a win/win situation.

This I suspect is why water companies are 'relaxed' about people using rain water for toilets etc. Technically, householders by putting more water into the sewerage system could/should be charged extra for sewerage.

However it would be almost impossible to measure how much extra water was entering sewerage system. Even if they could raise an extra charge on those householders, it would have no impact on their profits.

Also as mentioned above water companies assume that around 90% of supplied water enters the sewerage system(the percentage varies with companies), if you can prove that less than 90% enters the sewerage system, you can claim a reduction in your sewerage charge.

Martyn1981

Cardew wrote: »

This I suspect is why water companies are 'relaxed' about people using rain water for toilets etc. Technically, householders by putting more water into the sewerage system could/should be charged extra for sewerage.

For the many millions of properties with combined sewers it will make no difference. The rainwater will make it's way into the foul system either immediately, or delayed via butts, water tanks and a toilet flush. In fact, such a system will not only reduce the amount of clean treated water 'purchased' but also the amount needing sewage treatment - though the 'added solids' will still be the same!

Mart.

Cardew

Martyn1981 wrote: »

For the many millions of properties with combined sewers it will make no difference. The rainwater will make it's way into the foul system either immediately, or delayed via butts, water tanks and a toilet flush. In fact, such a system will not only reduce the amount of clean treated water 'purchased' but also the amount needing sewage treatment - though the 'added solids' will still be the same!

Mart.

My reply was addressing the points made in post#11 i.e for those who are metered.

Does anyone know if water companies will make a fuss if they find out you are rainwater harvesting and you're connected to a mains sewer? Our sewage water bill is calculated on the amount of incoming water we use, so if we use 60 litres over the billing period, we're charged for the disposal of 60 litres of water into the sewers.

If our incoming water goes down to 30 litres because the other 30 litres is now coming from stored rainwater, our outgoing
water will still be 60 litres but we will only be billed for 30 litres. I just can't see the water companies allowing that to continue, especially if RWH becomes more mainstream?

Just had another thought. As the OP has mentioned, you get a rebate if your rainwater goes to a soakaway or other water
source rather than to a sewer. If you divert this into a rainwater tank and use it to flush the loo, then it's going back into the sewer system. Only the overflow from a full tank will now go into a stream. Again, I can't see the water companies allowing people to keep this rebate when most of their rainwater
is going into the sewer.

Martyn1981

Cardew wrote: »

My reply was addressing the points made in post#11 i.e for those who are metered.

So was mine, just pointing out that not all properties have separate drains.

Mart.