enteron – the smallest sewage water treatment plant for yachts & boats

what is the enteron?

the enteron is a comletely biological sewage water treatment plants for boats

The Enteron is the smallest, certified fully biological Sewage Water Treatment Plant for Yachts and Pleasure Boats on the market today.

enteron sewage treatment plant by Mactra MarineSewage from the vessel’s toilet is pumped into the Enteron.  Bacteria is added once a month in the form of a small ‘teabag’ flushed down the toilet. The bacteria inside the tank simply eats the waste. The Enteron uses a macerator pump to break down the solids and the effluent is moved between the tank’s three chambers. Air is added to speed up the process. The Enteron is electronically controlled and will discharge 50 litres a day of bacteria free water into the watercourse via an ultra-violet filter. No chemicals are used in the process. The Enteron has Marpol & IMO world accredited certification from Germany where the unit is made.

Each Enteron comes with its own user friendly testing kit.  By drawing off a small sample from the inspection valve, this simple kit allows the user to carry out frequent checks to make sure that their discharge conforms to consent limits. The kit tests for Permanganate Values (PV), PH to test the acidity/alkalinity. A Turbidity Tube to test the clarity of the sample and a thermometer to monitor the sample tests.

It is possible to derive an indication of the biochemical Oxygen demand (BOD) and Total Organic Carbon (TOC) from the results of the Permanganate Value test.

living with an enteron

wide beam boat with enteron sewage treatmentThe Enteron 50 is aimed at a vessel with between 2 & 4 occupants and the treatment of their black water waste. It can be used to take grey water as well, but a larger version of the Enteron would be required to cope with the volume. Care has to be taken when adding grey water, as the chemicals used in cleaning processes can damage and kill the bacteria that make the Enteron so successful.

Padded toilet paper, and wet wipes are a no go for the Enteron. They can block the pumps and internal chambers. Standard toilet paper is quite acceptable and widely available Eco friendly cleaning products will present no problem to the Enteron.

Having friends to stay will result in greater use of the ‘facilities’. The Enteron has an overload facility which with greater use of the pumps, will allow a larger volume of waste to be treated for short periods.

The Enteron is a sealed chamber, the air vent has a carbon filter which mean the whole process is odourless. The pumps do make some noise when they cut in and out for short periods daily, whilst going to ‘sleep’ at night.  A weekly maintenance routine that can be carried out in minutes, will ensure that the operation of the Enteron will remain free from sludge build up. An annual change of internal filters can be carried out by the user or an authorised agent.

enteron on inland waterways

One of the most asked questions is “Does the Enteron have Environment Agency Approval?”

On asking the question to the Environment Agency, the response was:
The Environment Agency cannot endorse commercial products and it would be the manufacturer's responsibility to provide test results in support of any application.

Here is a link to the Thames general bylaws concerning the use of toilets.

Similarly the Broads authority have regulations prohibiting discharges from boat toilets.


The Enteron has internationally recognised certification to show that it complies with legislation: http://www.mactramarine.co.uk/marine-equipment-enteron-5-certificates.htm

A simple spread sheet program or paper recording sheets are supplied with every Enteron. This allows the user to record the results of their weekly testing for inspection if required.

technical data

Enteron 50 12V or 24V  120W
Dimensions 1500mm x 600mm x 550mm high
Daily load sewage water [l/d] - 50
Recommended for persons on board - 2 to 4
Overload up to [l/d] – 100 (temporary use)
Empty weight [kg] - 50
Weight at maximum load [kg] - 260
The daily consumption of a standard system, designed for two people, is about 17Ah (12V)

Enteron 80 12V or 24V  120W
Dimensions 1500mm x 1000mm x 550mm high
Daily load sewage water [l/d] – 80 to 120
Recommended for persons on board - 6 Plus 2
Daily consumption very similar to the Enteron 50 above.

other frequently asked questions:

Is the Enteron Expensive and why?

It took years to get the expensive testing done to gain the certification that makes the Enteron so unique as the world’s smallest fully certified biological sewage treatment plant designed especially for boats.

can I afford to buy and fit an enteron on my boat?

The Enteron 50 costs £7525.00 Plus VAT if applicable. As a retro-fit on a low value vessel this may not be a viable option. On a new build or to retro-fit on a newer vessel, the Enteron is a very viable option. ( There may be an option to buy VAT Free, if the vessel is a ‘qualifying vessel’ as per HMRC  guidelines).

The installation of the Enteron is straight forward and can easily be achieved by an owner or boatyard.

how will an enteron change my life onboard?

The obvious first change will be no further need for the regular move to a marina with a pump out facility and no basing of cruises around this. For those living statically onboard their vessels, there is no need to plumb into the main sewage system. But more than this having an Enteron onboard reflects a state of mind, of self-sufficiency and a care for nature and the environment.

Jim  MacDonald
Mactra Marine Ltd.

"We believe that the products that we sell are the very best available on the market today. We have overseen hundreds of installations by boat builders, marine engineers and by owners themselves. Our equipment is fitted on vessels ranging in size from super yachts to ocean rowing boats. As sailors ourselves we use this marine equipment on our own boat - so we know exactly how each product works."
Jim & Ann MacDonald