How much can I save with a soakaway? (Thames Water)

mrodent33

I have a semi-detached house in South London with a fairly respectably sized back garden. I would like to set up a soakaway as cheaply as possible and direct at least some of my runoff rainwater into it.

I am an exceptionally low water-user, and it is disgraceful that my standing charges are so high: it's bad enough for incoming water, but totally unacceptable for the wastewater.

However, in order to understand the value (feasibility) of actually thinking of doing this I need to understand exactly what I can save. Naturally enough this information is not easy to find on Thames Water's website (or I haven't be able to find it). Specifically:

My latest bill (just received) says I consumed 5 m3 over the last 6 months. Total charges £118. Of that the fixed charge for waste water is £65 and £7.74 metered volume (i.e. for the 5 m3).

Clearly some waste water is sewage from the soil pipe. Some domestic waste water is non-soil, but from sinks/basins/baths. I'm therefore anticipating that only a tiny proportion would be recouped if I could prove I had a soakaway. But the question is: can this result in reduced **fixed** charge for waste water, or does it only affect the metered volume? Clearly, in my case, if it only affects the metered volume charge I can dismiss this and never bother to think about it again.

If, on the contrary, there is a possibility of reducing the fixed waste water charge, where can I find how much I stand to save? In my case runoff rainwater directed to the soakaway would only apply to the back of the house (unless I did some massive work to make all the gutters at the front somehow flow round to the back). 

Thanks.

QrizB

I think you're on a hiding to nothing here.

If you can divert all your rainwater to soakaways, you can claim a rebate on the surface water drainage part of your waste water bill. But I don't think there's any scope for a partial rebate if you only divert half of it.

To divert foul water, I think you'll need planning permission and building regs for a septic system.

mrodent33

QrizB said:

I think you're on a hiding to nothing here.

Thanks. I think you're likely to be right.

If you can divert all your rainwater to soakaways, you can claim a rebate on the surface water drainage part of your waste water bill. But I don't think there's any scope for a partial rebate if you only divert half of it.

To divert foul water, I think you'll need planning permission and building regs for a septic system.

To clarify: I never considered any possibility of diverting foul water. Smelly job. More smelly than I even want to think about. My neighbours might feel the same way possibly.

OK, but let's assume I can divert ALL my rainwater round to the back, and to a channel which leads to the soakaway. The main gist of my question was: does the reduction apply to **all** waste water charges, or only to the **metered (i.e. proportionate to volume)** charges? Because the standing charges are so abusively disproportionate, someone in my situation would only consider looking into this question if a significant reduction in **standing charges** could be possible.

QrizB

The surface water rebate is a fixed sum. I think it's £20-30 per year.

Edit to add:

Someone recently repoted getting a rebate for the previous six years (as they'd alwayd had a soakaway) and that it was £200, so ~£33 a year.

https://forums.moneysavingexpert.com/discussion/comment/81603056/#Comment_81603056

molerat

Have you actually looked into the cost and how much work would be involved installing a soakaway and feed pipework ?  Do you have any driveway / impermeable areas that run off into the road - if so you would need to take the water from them as well to get a rebate.  You need a 1 cu m soakaway basket for 50 sq m of drained surface or 3 cu m of suitable rubble and it would need doing properly to prevent you flooding the neighbour's gardens.  You can't just dig a hole and hope for the best - you might get away with it if a single house in the middle of nowhere but not with other houses around. Building regulations part H refers.  The rebate does seem to vary with how you are billed.

mrodent33

molerat said:

Have you actually looked into the cost and how much work would be involved installing a soakaway and feed pipework ?  Do you have any driveway / impermeable areas that run off into the road - if so you would need to take the water from them as well to get a rebate.  You need a 1 cu m soakaway basket for 50 sq m of drained surface or 3 cu m of suitable rubble and it would need doing properly to prevent you flooding the neighbour's gardens.  You can't just dig a hole and hope for the best - you might get away with it if a single house in the middle of nowhere but not with other houses around. Building regulations part H refers.  The rebate does seem to vary with how you are billed.

All I've done to date is a random bit of googling... some people have reported being able to get away with a 1 m3 hole in the garden, and that that was just accepted. But ... 1) that may have been some time ago 2) that may not have been in a quite built-up area, as where I am (although Bromley, where I am, is almost semi-rural compared to parts of London I've lived in) 3) that may not have been in the Thames Water catchment area, where they're probably the most evil water company in the country ... etcetera ad infinitum.

You may have detected a scepticism in my tone from my question onwards. So yeah, £30 a year, sounds about right. I wouldn't scratch my arch once for £30 a year. And another consideration is that Thames Water would probably benefit (as profits) to the tune of 3 times that if I went to all that massive trouble. I would walk a million miles to prevent Thames Water deriving any more profit from me than I'm currently forced to generate for its benefit in the UK in 2025.

GrubbyGirl_2

Just to give you an idea of cost I had to have my rear soakaway replaced 4 years ago as it started to collapse.  I live in the south east so costs tend to be slightly higher but it cost me £3,500.  The previous soakaway was simply old rubbish that had been thrown in including plastic planters bits of metal, old rubble, a gnome and a pond liner all of which had to be taken away.  You'll still have to have your waste taken away so will still be a cost.  It was replaced with a crate like structure with a concrete top which apparently has to be a minimum of 1 cubic meter but I opted for one half as big again.  Of course I didn't need new pipework so you'll have to factor in that cost.   If you save about £50 a year it will take you 70 years to get your investment back.