Plumbers & electricians in Hayes and Keston

First the obvious clearing up: this is Hayes in Bromley, beside Hayes Common, not the Hayes in Hillingdon in west London. The railway came in 1882, but the village stayed small until electrification in 1925 halved the run into town. The station was rebuilt in 1935 and the Hayes Place estate laid out in 1933, so the roads around it are mostly interwar.

Shortlands is a different age of building. The station opened in 1858, and the break up of the Shortlands House estate put large Victorian villas along the slopes of the Ravensbourne valley, with the twenties and thirties filling in between. Those houses have been altered repeatedly, so much of the work in them is second fit: bathrooms and shower rooms carved out of old dressing rooms, and boiler repair in Hayes and Shortlands that starts by tracing where things run.

South past Hayes Common and Keston Common the character changes properly. Keston sits on the free draining sands and gravels of the Blackheath Pebble Beds, and the Ravensbourne begins here at Caesar’s Well. Beyond it the A233 drops to Leaves Green, beside Biggin Hill airfield, where a planned nineteen thirties estate never happened because the war and then the green belt stopped it. Ribbon development, farmland behind, and houses with their own driveway, their own supply run and sometimes their own drainage.

Why some houses at Keston and Leaves Green treat their own sewage

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Public sewers follow dense building, and where houses went up in twos and threes along a lane rather than as an estate the sewer often never arrived. Two very different things then get called a septic tank. A true septic tank has no power and does no real treatment: solids settle, grease floats, and the liquid drawn off the middle leaves still contaminated, so it has to soak slowly through soil that finishes the job. A treatment plant is a machine, with an air pump and a bacterial process inside it, and what comes out is far cleaner. That difference is the whole of the regulation. Under the General Binding Rules in England a septic tank has not been allowed to discharge to a ditch or stream since January 2020, and a discharge to a watercourse now has to come from a treatment plant that meets the required standard.

Failure never announces itself. What people notice first is small and easy to blame on something else. The downstairs toilet goes lazy and wants a second flush. The bath empties more slowly in February than it did in July. There is a smell in the garden on a still evening that was not there last year. Then a strip of lawn over the drainage field stays greener and softer than the rest and never quite dries after rain. Four symptoms, one problem, and the problem is usually the ground rather than the tank.

Two things decide whether these systems keep working, and only one is cheap. The first is emptying, at least once a year for most households, because when solids carry over into the outlet they clog the drainage field and that damage does not reverse. The second is the field itself, which is not a rubble pit but a designed run of perforated pipe in trenches, sized from a percolation test on that plot. So the honest answer depends on the property: the sand and gravel on the high ground around Keston can percolate well, while wetter or heavier ground close by will not. It is also why the usual fix is often the wrong one. Emptying more often will not rescue a field that has stopped taking water, and nor will dropping a new plant onto the same saturated trenches. What resolves it is a correctly sized field, or a treatment plant meeting the required standard where the discharge goes to a watercourse, or a connection to the public sewer where one is reasonably accessible.