Your Complete Guide to the General Binding Rules for Off-Mains Drainage

Since 2020, the Environment Agency’s General Binding Rules for Small Sewage Discharges has been in force. Hutchinson’s Definitive Guide will help you to understand how the new rules apply to your property or business.  

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If you own or live in a property with either its own or a shared septic tank or sewage treatment plant then the new general binding rules might apply to you. Our guide will help you understand the rules and how they might affect you. 

The Environment Agency (EA) is part of the Department for Environment, Farming and Rural Affairs (DEFRA). The EA’s responsibilities include: 

  • regulating major industry and waste
  • treatment of contaminated land
  • water quality and resources
  • fisheries 
  • inland river, estuary and harbour navigations 
  • conservation and ecology. 
 
The EA has jurisdiction over all water resources in England. They work to protect them from pollution and improve water quality in line with legislation and environmental targets. If you cause water pollution, knowingly or unknowingly, the EA will work together with you to stop and prevent further pollution. If you fail to cooperate with the EA to prevent further pollution, the EA will be forced to take further legal action against you. 
 

The new General Binding Rules for Small Sewage Discharges is part of the EA’s work to protect water resources from pollution caused by Small Sewage Discharges. The rules acts as a quid pro quo for not having to apply for a permit. In making a Small Sewage Discharge without a permit, you are bound by the General Binding Rules. Ignorance of the General Binding Rules is not a defence for not complying with their requirements, in the same was as not knowing the speed limit is not a defence against breaking that limit.

 

FAQ

Under the General Binding Rules, Small Sewage Discharges can be made without a permit to 3 types of “receptors”:

  • Fresh surface waters, e.g. most commonly streams and rivers, but also inland lakes, tarns, ponds, etc. provided that they’re not enclosed or, if they are enclosed, provided that the discharge was “existing”, i.e. being made, before 2015. For “new” discharges, i.e. that commenced in 2015 or later, to enclosed lakes, tarns, ponds, etc. a permit is needed, see rule 21 below.
  • Marine surface waters, e.g. estuaries and coastal waters, up to 3 miles out.
  • Groundwater, i.e. any and all water underground (even if it’s 1mm below the surface), through a drainage field, infiltration field, leach field, call it what you will, but what it’s most often called, incorrectly, is a “soakaway” (see question 4 below)

Discharges totalling less than 2000 litres of wastewater per day can be made from a septic tank or from a package sewage treatment plant “to ground”, and therefore sooner or later to groundwater

Discharges totalling less than 5000 litres of wastewater per day can be made “to surface waters” from a package sewage treatment plant

Calculate how much wastewater your domestic property or group of domestic properties produces (see below for commercial properties)

Wastewater production is accepted by the EA to be 150 litres/person/day in a domestic situation

  • 2000 litres equals 13 people’s domestic wastewater production per day
  • 5000 litres equals 33 people’s domestic wastewater production per day

Outside the home, e.g. in offices, hotels, cafes and restaurants, leisure centres, camping and caravanning sites with toilet blocks and showers, etc., the figure is not 150 litres/person/day: the total volume to be discharged per day must be calculated by site and at peak usage in high season by referring to British Water’s Code of Practice: Flows and Loads – 4: Sizing Criteria, Treatment Capacity for Sewage Treatment Systems, e.g.

    • In a rural office, 2000 litres could equal as much as 40 staff’ wastewater production per day – a large office, for a rural location
    • In a luxury hotel, 2000 litres could equal as little as 6 guests’ wastewater production per day – a very small hotel, anywhere – just 3 double bedrooms

The purpose of a “soakaway”, as the name suggests, is to allow water to soak away. That’s fine for clean rainwater that needs no treatment but not for wastewater that does.

Rain usually falls more quickly than the ground can absorb it. Impermeable surfaces such as roofs obviously don’t absorb it at all, so it’s carried away through gutters and downspouts to gullies and then to an underground soakaway pit. The soakaway holds the rainwater and allows it to “soak away” into the ground at a rate the ground is able to accept it.

A soakaway has traditionally been a rubble- or gravel-filled pit measuring approximately 1m x 1m x 1m for up to 100m2 of roof area. “Crates” are now often used to create the necessary supported underground void to fill with rainwater. Having a floor area of 1m2 a soakaway offers no dispersal over a wider area to prevent total saturation and thus any form of aerobic wastewater treatment is prevented. Rainwater is clean enough to soak away back into the water table without treatment: sewage isn’t.

“Do crates work for sewage treatment?” No: why would they? It doesn’t matter what the soakaway is filled with, what matters is that a 1m x 1m x 1m soakaway concentrates the flow of water into the ground in a 1m2 area which quickly becomes saturated and therefore cannot support the aerobic microorganisms that digest the contaminants in the sewage.

“What if I use lots of crates in a line?” OK, we’re getting closer. But you need the trench floor area as required in the British Standard for drainage fields. And you need the wastewater to flow along the whole length of a trench, so it’s evenly distributed and no one part of the trench is overloaded. Can you dig a trench with a 1:100-200 fall? By the time you’ve done all this, it’d be cheaper (and more effective) to build a conventional drainage field.

“What about anaerobic bacteria?” Good question. Anaerobic bacteria are about 10 times slower than aerobic bacteria at doing the same job, so the wastewater would need to pass by them 10 times more slowly. But soil doesn’t just contain bacteria: it contains a whole food chain of microorganisms, all of which are aerobic, and it’s their total effort that’s necessary. And in the meantime, you have a soggy, black, foul-smelling wet patch in your garden, over your soakaway.

If a contractor builds you a rainwater soakaway for sewage treatment, you (and not the contractor) are contravening Building Regulations. Does that matter? Well, you’ll be polluting groundwater in contravention of the General Binding Rules (Rule 4 – “Thou shalt not pollute”). When you come to sell your house you either have to spend the money you should have spent in the first place to put it right or accept a lower price from the new purchaser for them to put it right.

If you use a rainwater soakaway in an attempt to treat sewage you will pollute the water table. How would you know? You probably wouldn’t because you can’t see the pollution. How do we know? Experience: we’ve dug them up, see what they look like and know what that means in terms of effective physical and biological treatment.

There is no law to say you can’t drink it, in the same way, there’s no law to say you can’t drink diesel, rancid milk, etc. It’s probably no worse than drinking water from a beck just downstream of a busy farmyard that will contain some partially digested organic matter, Weil’s disease bacteria from rats’ urine, general bacteria that live on sewage, plus viruses and bacteria from the human gut, present in faeces and urine, that are able to survive outside the gut and longer than the retention time of the treatment plant… Does that answer your question? If not, for the avoidance of doubt, no, don’t drink it. It’s not a sound sales argument to say that if a liquid appears clear to the naked eye it’s fit to drink. If you’re determined to drink something unpalatable, the water in the toilet bowl after you’ve flushed contains fewer pathogens and is more easily accessible. As is the phone to call a doctor immediately afterwards.

The General Binding Rules

The General Binding Rules are explained, in order, one by one. Rules 1-14 apply to ALL discharges, regardless of when they started, and rules 15-21 to discharges that started in 2015 or later. To find out more, just click the rules below to expand for more information.

We hope this helps you, whether you’re looking to build a new house without access to mains sewerage, an architect designing someone’s dream home, buying a house with a septic tank or are already the owner of a problematic package sewage treatment plant. If you have any questions or would like some impartial advice on how to treat your wastewater responsibly and effectively please do just get in touch: the benefit of our experience over the phone is free, as is a site visit if you really want one. In England we concentrate our domestic installation work in and around our home county of Northumbria, so Cumbria, Durham, Tyne and Wear, Cleveland, north, east and west Yorkshire and across into Lancashire. Although travelling further afield costs more our national clients tell us that we still offer very good value for money and peace of mind for more involved commercial installations on difficult sites where compliance is critical.

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