The Brew Cabin

Hi Brush,

1. From what I have read, I will not be able to discharge any surface water into the sewers unless they are combined drains. How do I find out if they are combined drains or just for sewerage?
Mmmm. By discharging SW into a FW sewer, you are rturning it into a Combined sewer. Your LA, as agent for the water authority, may not be best pleased with this, as it increases the load on the Effluent Treatment Works, but then again, they might accept it if there is no viable alternative. You will need to speak to the Tech Services Dept at your LA to ascertain their stance and to find out whether the existing swewer is Foul, Surface or Combined.

2. Would I be able to connect into the road surface water drainage to get rid of some of my surface water if the drains are just for sewerage?
You need a permit to connect to a public sewer and your need a permit to excavate in a public highway which involves several million quids worth of insurance cover, a competence certificate, inspection fees to tyhe LA, and lots of other bureaucracy designed to ensure private householders are deterred and the job is left to the so-called professionals. Again, while this is a possible solution, you must get approval from your LA first.


3 Pump and land drain option
I'm unsure how this would work. Using a float switch to activate a pump is straightforward enough, but to where would it pump? The excess water has to have somewhere to go - can you explain your layout a little more?

I have a similar problem to Brush, ie a waterlogged back garden (in my case thick Cheshire clay soil.) The garden slopes away from the house so the surface water is higher than the low point of the drains.

To a novice like myself a submersible dirty water pump with a float switch looks like a relatively simple option (£100 from Draper Tools). I know you have advised against pumping due to price and complexity. However, digging a relatively small sump and placing a pump at the bottom seems on the face of it easier than digging a large soakaway that probably wont work anyway due to the high water table.

I could bury the electric cable (RCD prptected) and the waste hose under the lawn. The waste hose could discharge into an existing trap by the house that serves a downspout. This is a 1930s house, so it may be a combined waste system, I'll have to check.

Given your years of experience, is this a viable option, or wishful thinking? Thanks for the excellent website btw.

What you're proposing is a small-scale version of what we call a Wet Well and Rising Main arrangement. Basically, the 'effluent' (in your case, surface water) is collected in a sump (the Wet Well) and, when a pre-determined volume is present in the sump, a float switch is triggered and the excess is pumped uphill, via the Rising Main, to a convenient outfall - the trap by the house, for you.

This is a proven scenario and is used on many sites up and down the country but, there can be all sorts of problems when the system is adapted for use with a residential soakaway, and I'll just guide you through the two most commonly reported 'issues'....

1 - The pump fails. Often, the water in the sump is rich in sediment and/or clay particles and, unless a suitable pump is used, the wear and tear is such that many pumps, often those commandeered from a garden pond or waterfall, just cannot cope and burn out or silt up and burst the valves. The Dirty Water pump you mention is one of the better models, but even so, you need to check the filtration on a regular basis.

2- Where's all this bloody water coming from?
As soon as you create an effective 'outfall' for groundwater, you initiate a re-structuring of the natural groundwater channels in the surrounding area and you can find yourself draining every other bugger's garden. Think of groundwater as a gradient - we call it hydrostatic pressure. As soon as you start pumping, you are lowering the pressure at your 'sump pump' and thereby increasing the gradient within the local area. Now, all that other groundwater that once found or forced its way via the neighbouring land to a ditch or other outfall now makes a beeline for your snazzy new invention, and the next thing you know is that the damned pump is running 24-7 and you're paying for the lecky!

This is why I urge caution when considering the installation of this type of solution. Yes: it can and does work, but, in the wrong conditions, with the wrong kit, in the wrong location, it can create more problems than it solves.

If you do go for this solution, I'd strongly recommend a generous Wet Well, something like a 1050mm diameter circular MH chamber or a 1000x750 rectangular section, and, most importantly, a silt trap/catch pit to keep the Well as clean as possible.

Ensure any land drainage sytem feeding the Well is membrane-wrapped to reduce silt/sediment, and keep the rising main well buried for frost protection. We keep water supply pipes 900mm deep, but you could get away with an absolute minimum of 300mm for a small residential Wet Well and Rising main scheme - 450mm would be better still.

Also consider the outfall point. It's better to outfall within an existing IC or MH (for frost protection) than to bring the water up to surface level and dump it into a yard gully or rainwater pick-up.

If you do go ahead with this, I'd like to hear how you get on, and what your time and material costings run out at, as it's not something I would normally suggest as a DIY job.

Good luck!