drains and manholes, part one

[Fred]

Hi,

Some may remember that my patio does not have a slope nor any drainage, so when it rains heavily, water pools.

The slabs are uneven so I would like to lift and re-lay the patio one day, and would include a slope and drainage at that time.

I know one option is to dig a soak away but I have clay soil, and I am not very eager to dig a big hole; the less digging the better for me!

I wondered whether I could install some drains. I thought that modern houses had separate rain and foul water drains and that my mid-70s house would fall into this category but now I am not so sure.

My kitchen is on the rear of the house and the bathroom is on the side. On the drive I have a manhole. If I lift the manhole there is a tee. The branch comes from the soil stack from the bathroom and I imagine the kitchen drain comes round the corner and goes into the other end.

My drainpipes are at the front of the house but I cannot find a separate manhole for them, so I have no idea where they go. Would the rainwater drain have a manhole, or are these only for foul water drains?

Is there any way of finding where these rainwater drains, downstream of my manhole, go?

There is a down pipe on the garage and when I run my hose pipe into this, water flows through my manhole, so I imagine this tees into the kitchen drain. If this rainwater drain goes into the same sewer, isn't it reasonable to assume those at the front of the house do too?

I also have a small (4"?) metal cover on the drive at the kitchen end. If I unscrew this there is a clay pipe that drops and bends; after that I don't know where it goes. I assume it is a rodding point for where the kitchen drain comes round the corner and onto the drive. Again if I run a hose into it, water flows through the manhole.

Whilst the patio is dug up, would it be practical to lay some 110mm pipe and tee into these drains, including a rodding point or inspection chamber as appropriate?

Is there any way to find out where the pipes are buried beforehand or is it just a matter of being careful when you dig and plumb according to what you find?

TIA

[Brian Gaff]

There are some odd things done of course. A guy down the next rod to mine has for some weird reason, a drain in the front of his hous on a hard standing that empties into the same drain as lie under the road outside. whether this is general for front hard standings is debatable as most of the other houses don't have them. Very odd.

Brian

[Hugh - in either England or Sp]

I would imagine with a 70s house rainwater from the roof, patio etc. should be directed into soakaways or on to your land.

[Andrew Gabriel]

This depends where you live. There are basically 3 options for the rain water drainage:

1) In old dense urban areas (like London, pre-1900 build), there's often only a single drainage system which has to take both foul and rainwater. This can flood sewage treatment in heavy rain, so it's not been used for a long time in new builds. 2) In newer dense urban areas (London post-1900 build), there's usually a separate rainwater drainage system to take rainwater away from properties, and channel it into local streams/ditches without treatment (or just an oil trap where road run-off is included). This can flood too, but it's only rainwater, not sewage, so it's not so bad.

In the 1920's version of this that I'm aware of, the rainwater drains are just below and slightly offset from the foul drains. They are accessed via the foul manholes, where there's a second access cover inside the foul chamber (cast iron disc sitting on the open end of a vertical clay pipe which sticks up above the benching, which goes down to the rainwater pipe).

3) Where properties have space for soakaways (land which is some distance from any building, such as a garden), soakaways are used rather than taking the rainwater off property.

Your options would therefore be to dig a soakaway, or to get permission from your local sewage company to connect a rainwater drain to their sewer, which they will sometimes allow if they have capacity for dealing with the extra rainwater at the local sewage system. However, note that they now have the ability to charge for all rainwater leaves your property via surface or piped - this is currently only being done for commercial premises, but will be done for residential premises soon too, and possibly immediately if they grant you permission for a new connection.

If you can see into the pipe in the ground, look to see what direction it heads off in. Then push the hose down it as far as it will go, pull out, and measure the length. Quite likely, that's how far to the soakaway. Nowadays, it will be about 5m, but might be less for older properties and/or smaller plots. If the soakaway is a large capped tank construction, then the hose will keep going in, but that's probably unlikely on domestic premises, where it's more likely to be a large hole backfilled with large stones or rubble to prevent collapse.

No. You might well find the garage one shouldn't, if permission to do so wasn't granted by the sewage company.

There will have been plans. Depends if anyone still has copies. You local authority may.

[Brian Gaff]

I guess you could always get creative, get a rainwater butt and a little pump and dig a hole and when the water comes over the pump pump it into the butt. Brian

[Harry Bloomfield]

Soak aways do not work well or sometimes even not at all in clay soil.

The water just collects and with no way to escapes, will just overflow.

[Hugh - in either England or Sp]

Neither the surveyor when I bought this house (nor myself since of course ;-)) noticed that there is an extra outlet below below ground level into the outside drain that serves our cloakrooom whb. Pure coincidence that after heavy rain roof type detritis ends up in there. Nothing to do with the downpipe serving half the roof which descends a couple of feet away into an ageing soakaway.

[David WE Roberts]

I seem to remember that water rates included charges for removing sewage, grey water and rainwater. At one time you could get a reduction in your water rates if you could demonstrate that all down pipes went to soakaways or onto the garden, and none went into the sewers. This does seem to assume that the default is at least some rainwater going into the sewage system. This was a decade or so back, though. Our previous house had a gulley at the front which took rainwater into the fould drains.

We are told by the BCO that the rainwater from our extension will have to go into a (new) soakaway unless the water authority agree that it can go into the foul drainage.

I assume that the default for rainwater could be the storm drains which run along the roads - seems logical - but nowhere around here in the '30s houses seems to be linked to it.

IIRC there was a soakaway at the bottom of our drive where I lived as a young lad, which had an overflow back out into the road - presumably to the storm drains. The drains must have been pretty deep as we were well downslope from the road.

Cheers

Dave R

[Phil L]

Rainwater doesn't have, or need, a manhole

not by you, but if you connect foul into rainwater system, you'll get a knock at the door within 6 months

Yes, around here there's very few properties have seperate systems

Yes, but you don't need a rodding point or manhole - water runs freely- it's only sewage that blocks up

Start at the drain you are going to break into and work back to the patio. I normally use channels on the drive / patio and run a pipe from this to the nearest manhole / sewer / whatever.

If you can break a hole in the side of the manhole, then I'd go for this option.

Forget about asking / telling water boards etc, you're already paying to have surface water treated and this is no different, also, surface water can't be traced in sewage but sewage will be traced if it ends up in a local brook

[charles]

not quite true. Moss off a roof can get into the drain and does cause a block. I've had to open up a soak away and rod the rainwater drain.

[Andrew Gabriel]

Oh yes it can*, and Thames Water did such a check about a year ago in the 1920's area I referred to, and forced all households to fix all the wrong connections to sewage and surface drains which had built up over the years.

*It's initially spotted by the foul drain volume increasing during rain, and then traced to the source and verified by using different coloured tracer dyes. If you have any wrong connections, you are charged a survey fee for the investigation, in addition to having to get the connection fixed within a time period (which they hand over to Environmental Health to enforce, and they serve a notice on you).

Fortunately, this had all just been corrected by the time my friend moved in, and the only fault in his house had been the washing machine discharging into a surface water drain, but some other households had to have some major drain reconstruction.

[Phil L]

You are telling me that a water authority can notice a volume change when one person runs surface water into the sewer?

If you have any wrong connections, you are

Yes, a builder I know connected a bog to a rainwater drain. Six months later they told him he had to put it right, which he did, no fines, fees nor anything else.

Fred's already pointed out that all his rainwater goes through the same manhole as his sewage, I don't think it's seperated further down the line

[Andrew Gabriel]

They investigated an area (at least a whole road, but it may have been much more than that). I would guess they were seeing an increase at the sewage [pumping] station when it rained, which shouldn't happen with separate systems, and/or they saw suds floating in the local brook. They then checked all the houses, and many houses had to fix things.

Fine if he's sure that's how it's supposed to be in his area.

[Tim Lamb]

In message , Andrew Gabriel writes

Properties in our lane were all built with septic tank sewage systems.

Thames Water put in a pumping system and new sewer pipe to collect waste. At the time, they were quite keen to take yard and dairy washings as they believed it would help minimise sediment and subsequent maintenance. In the event, my father opted to retain the existing *dirty water* disposal system for the dairy but agreed to have the domestic system connected.

Much later, we bought a chalet bungalow in the lane. Much as the OP, I discovered that the rainwater combined with the sewer outfall. Presumably this was not an issue with septic tank treatment.

I think that the sewage authority were fairly relaxed about rainwater when they were persuading people to give up their septic tank systems.

Building control have required soaks for all subsequent development.

regards

>

[Andrew Gabriel]

You can always ask the local sewage operator if you can discharge rainwater into their sewer, and they will sometimes say yes. It depends on the spare capacity and design of the local system. You must keep the letter granting such permission very safe though (traditionally with the house deeds, although they mostly don't exist anymore), as LABC tend to lose such things, particularly when council boundaries move.

[Fred]

Our bill does a charge for taking rain water, so does this mean rain and foul water share the same sewer? Or do people with separate rain and foul sewers still have to pay? After all, even if you have a separate rain drain, I presume the water company still has to maintain it and they charge for that?

The charge is all or nothing, so you have to have all down pipes connected to water butts to be exempt. It is a shame that you cannot get a 50% reduction for having half of your roof connected to butts, as it is very difficult to connect all down pipes to butts if you have down pipes at the front of your house.

[Fred]

I'm not sure I have a soak away because it is clay soil here and also, I'm not sure the garden is big enough. Another post said 5m from the house; that would be next door!

Surely it would be easier for builders to lay drains rather than dig soakaways in each garden?

[Fred]

My water butt collects moss and rubbish off the roof, so I thought that might cause an occasional problem?

I think the manhole is too far away and round a corner, so it would be easier to tee into the kitchen drain if that is allowed. Also, I have not done any work on manholes before so making a hole and adding an outlet would be something outside my comfort zone, whereas I could happily fit tee pieces into pipes.

[Andrew Gabriel]

They can also charge for surface run-off, e.g. from your driveway into the street. I don't think the charge relates to the method the water leaves your land, and you are only exempt if it all soaks in to your ground.

I doubt water butts make any difference. Still need to consider where the butt overflows to.

[Fred]

Why is it that if you have solar panels or a wind turbine and you give the electricity companies electricity they pay you but if you give the water company a relatively pure supply of water they charge you?