Septic Tanks

Marsh Septic Tanks – Tested & Certified to EN12566-1

Marsh Septic Tanks - Tested & Certified to EN12566-1

TUV 12566-6 Certificate

Marsh septic tanks are either “traditional Onion shape septic”or the low profile cylindrical tanks that are designed for high water table or hard rock conditions. Marsh Septic Tanks can normally be installed in pea-shingle, they are tested and certified to EN12566-1, but for discharge into a landrainage system not ditch or watercourse. The septic tanks come complete with cover and frame. The septic tank is fitted with two Lloyds registered lifting eyes or slinging points. Delivery is normally four days from ordere placement. Installation in normal ground conditions is a pea shingle surround but concrete must be used for high water table areas. No power is needed for this tank.This septic tank is certified for installation throughout the EU. Manufactured in virgin resin (no chalk filler) and glass. If the property you are fitting this too is a new dwelling it would be advisable to check that Building Control will accept a septic tank in preference to a Ensign sewage treatment plant.

Ensign sewage plants are listed on these pages, they are extremly competitively priced and are tested to the highest european standards. We offer the option of Polylok Filters prefitted in the out let TEE piece of the septic tank, they are very easy to maintain, and prevent smell and the blocking of the soakaway. Marsh hold EN12566 certification for Domestic Sewage Plants, Uni:Gem and three complete individual ranges of septic tanks.

Septic tanks and cesspools have been used in the UK since the middle ages, thankfully we have come a long way in the design and functionality of sewage disposal since then. A packaged sewage treatment plant should be the preferred choice of sewage disposal if your property is not connected permission to install a new Glass Fibre septic tank, we can offer you two different profiles. The Marsh EN septic tank is produced in the traditional spherical “onion shape” and also in the low profile shallow cylindrical style. Both designs are fully compliant with UK building regulations and are also CE marked having been fully tested to EN12566-1.

Septic tanks can only be discharged into a percolation drainage system as set out in building regulations , not into a river, watercourse or ditch (only sewage treatment plants like the Ensign can be discharged into a watercourse etc.). Septic tanks are not suitable for areas of the country where the soil is of a heavy clay constitution. Septic tanks need to be regularly de-sludged to prevent the solids entering the drainage field. A porosity test to ensure the soil is suitable installing a septic tank must be undertaken prior to installation. Marsh septic tanks can be fitted with our unique patented Polylok filter. This filter further filters the suspended solids and prevents the percolation drainage field from blocking. Septic tanks do not treat the Ammonia levels in raw sewage, and only reduce the solids by less than 35% when compared to our sewage plants that reduces solids by 95%.

Shallow profile or low profile two stage septic tanks have become more popular in recent years, very often they are installed in areas of high water table or hard rock where the normal spherical tank with its deep profile is not a practical solution with the shallow tank being easier and more economical to install.

In normal ground conditions all septic tanks though should be installed on a 150mm concrete base and concrete surround (150mm). Marsh provide detailed installation guidelines in the installation handbook supplied with the tank. The handbook also covers installation in wet heavy grounds and details of porosity tests and drainage area design. The main failing of a septic tank generally takes place during the installation, where people do not read the instructions supplied or take short cuts. We do not produce polyethylene or polypropylene septic tanks, all of our septic tanks are manufactured using glass fibre and resin from UK leading companies, we do not use chalk or calcium fillers that reduce the strength of the resin.

We can produce septic tanks up to 20,000litres, as guide to size a septic tank you start with a base figure of 2000litres then add 150 litres per person. The smallest septic tank available from us is 2800L. We supply our septic tanks with integral lifting eyes and either flat bottoms (spherical) or with legs (cylindrical) for easier installation and health & safety compliance. Furthermore our unique “keying in” lip has tremendous installation benefits.


A cesspool is a watertight tank with no discharge pipe, no treatment is involve, the smallest cesspool allowed in in the UK for two people is 18000litres and then add 6800litres per person. To put this in perspective a 20000litre tank is 8m long x 2m diameter and requires approx. 20 tonne of concrete.

Cesspools are not permitted in Scotland. To choose a cesspool is an extremely costly long term decisions, with ongoing emptying by a registered waste carrier.

For advice on installation or size selection please call the Marsh Sales office on 01933 654582

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