Septic tanks on farm: Rules and replacements

By the time 1 January 2020 comes round, the Environment Agency hopes that farmers with septic tanks that currently discharge into a watercourse will have checked them and upgraded if necessary. Well, that’s the plan…

Why upgrade?

These new rules, which started coming into force in 2015, will cover all systems that treat waste water and sewage unless you are lucky enough to be already connected to the mains sewers.

“The rules are designed to reduce the level of pollution from sewage in the nation’s watercourses,” says Lucinda Thompson, assistant land agent at Strutt and Parker. “If the property is sold prior to this date [in 2020], then the upgrades must take place before the sale.”

Septic tank or cesspit?

Wondering what the difference is between a septic tank and a cesspit?

A cesspit is a single sealed underground tank that simply collects wastewater and sewage from a house or business with no processing or treatment.

All of which sounds great, until you remember that a high proportion of the septic tanks around the UK were built donkeys’ years ago and may require a certain amount of money to get them back into anything like smooth running.

So it could affect quite a few of us.

Most farms have a septic tank for the farmhouse, plus one or two next to cottages.

And it’s probably fair to say that they don’t get the love and attention that we might give to, say, a shiny 300hp Fendt tractor or gleaming MF combine. 

In contrast, a septic tank has two chambers, allowing solids to settle at the bottom and begin to decompose, while liquid flows through to the second chamber.

See also: All you need to know about lights in farm buildings

Smells and pollution

Anaerobic digestion systems reduce the volume of sludge and therefore the frequency of emptying.

Meanwhile, the resulting effluent flows quietly away to an underground soakaway.

It’s a well-used technology across the world – in the US, 25% of households have some form of septic tank and in France it’s 20%.

If it’s working well, that’s great. However, there can be problems, such as flooding in wet periods, bad smells, and pollution getting into ditches and streams.

Also, the latest January 2015 regs from the Environment Agency mean that if you can’t stop smells and pollution you may be forced to make improvements to enable compliance. That could be difficult to achieve, especially if you have clay soils that are boggy in wet winters.

The rules for septic tanks

Here’s a quick roundup of some of the rights and wrongs of septic tanks.

  • The discharge rate from a septic tank or small sewage treatment plant must be less than 2cu m/day.
  • The sewage must receive treatment from a septic tank and filtration system or a sewage treatment plant.
  • The sewage must be domestic, not agricultural.
  • The discharge must not cause pollution of surface water or groundwater 5m from a boundary, 10m from a ditch or watercourse, 50m from a water abstraction point or 15m from any building and other soakaway network.
  • The discharge must not be within a groundwater Source Protection Zone 1 or within 50m of any well or borehole that is used to supply water for domestic or food protection.
  • BS manufacturing standards must be adhered to and the system installed and maintained by a competent person.

Where can you get a septic tank?

There are more than 40 models of septic tank in the UK, and they come in all shapes and sizes. Most of them are from well-established firms who know the technology.

Tanks can be made of plastic, steel or concrete – the main types are onion (because it looks like an onion bulb), traditional (brick-shaped) and shallow dig (a flatter shape that needs less depth).

Manufacturers include Clearwater, Crystal, Graf, Hydroclear, Klargester, Marsh, Owlshall, Tricel and Vortex. Here are a couple of examples:

Clearwater Alpha

  • Style: onion
  • Size: 2,800 litres
  • Capacity: four persons
  • Dimensions: diameter 1,225mm, height 1,225mm, length 2,955mm
  • Inlet level to base: 1,565mm
  • Price: £440

Clearwater 2800 Shallow Dig

  • Style: shallow dig, so requires less soil disposal
  • Size: 2,800 litres
  • Capacity: up to four persons
  • Dimensions: diameter 1,225mm, height 1,630mm, length 3,020mm
  • Standard invert is 500mm, but can be increased to 1.5m in increments of 500mm
  • Price: £728

Marsh Ensign

  • Style: onion
  • Capacity: up to 10 persons
  • Dimensions: 1,950mm deep
  • Gravity or pumped
  • Should be 7-10m from the house
  • Price: £1,900

Tricel Novouk6

  • Capacity: up to six persons
  • Dimensions: length 2,100mm, width 1,640mm, height 2,240m
  • Air blower 60W
  • Price: £1,670

Tricel Vento 3000-litre

  • Style: shallow dig
  • Capacity: up to six persons
  • Dimensions: length 2,700mm, width 1,190mm, height 1,440mm
  • Price: £516

Case study: Nick Cousins, Essex

With three septic tanks spread over two farms near Braintree, Essex, Mr Cousins has had his share of dealing with tanks over many years. Mostly they have worked well in the first few years, but then problems start cropping up.

The oldest, an ancient Klargester, served a three-bedroom farm cottage from 1991 without too much trouble or smell. However, the motor finally packed up and unpleasant wafts became a regular nuisance when the wind was from the wrong direction.

New septic tank installed in the ground with plastic piping in a trench

So last year the farm replaced the Klargester with a £2,500 Vortex unit from Yorkshire company Crystaltanks.

Vortex claims it has the lowest electricity consumption of any electric septic tank and says its one-piece tank construction should ensure no problems with leaking seals.

There’s also an unusual vibrating screen that deals with baby wipes, tampons and other detritus.

It also has a simple hand-turned valve that can turn the amount of air required either up or down, depending on the number of people using it. It comes with a 10-year warranty.