Main changes of the 2021 Code of Practice

The Environmental Protection Agency (EPA) is responsible for protecting and improving the environment
as a valuable asset for the people of Ireland. The work of the EPA is divided into three main areas: regulation, knowledge, and advocacy.

The agency publishes a Code of Practice document about domestic wastewater treatment systems. Since June, 7th 2021, a new version is available. 

Code of practice changes

What does the 2021 Code of Practice change? 


The role of the Code of Practice (CoP) is to provide guidance on domestic wastewater treatment systems, published under Section 76 of the Environmental Protection Agency Act, 1992. The document concerns house with a population equivalent (PE) of less than or equal to 10.

The revision of the Code of Practice introduces operational and practical changes as well as new options available, including the latest disposal routes.

This new version applies to site assessments and subsequent installations carried out on or after 7th June 2021.

We will try to give you an overall panorama of the major changes that affect Tricel’s solutions.

Tricel Maxus Commercial Wastewater Treatment Unit

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The new disposal routes

In order to answer some on-site wastewater treatment problematics, that may have repercussions on health and the environment, the EPA made a research to find and investigate some alternative wastewater treatment and disposal options in an Irish context.

Here are some of the new disposal routes and how Tricel’s solutions can fit them.

Irish House in the countryside needing a septic tank

Disposal route options

Depending on the wastewater treatment solution you are looking for and the type of soil you have, there are several disposal routes options.

When the soil is located on sensitive sites such as water table protection areas, secondary and tertiary wastewater treatment is required. They allow further treatment of the effluent coming from the primary treatment tank. Those solutions bring a higher quality effluent, achieving a high-level pathogen and nutrient reduction.

Let’s have a look at some specific cases:

Secondary Treatment
Tricel septic tank  + Packaged filter system Puraflo 

As the Puraflo is a packaged filter system that uses a bed of coconut fibre to filter wastewater for treatment, it is one of the disposal routes of the Code of Practice 2021 (section 8.2.1 of the document). This wastewater treatment system meets the requirements of SR 66 and I.S. EN 12566 Part 6. Have a look at how does the Puraflo work.

Secondary Treatment
Tricel Novo (sewage treatment plant)

The wastewater treatment plant Tricel Novo works with a submerged aerated filter (SAF). In this system, aeration, settlement and decanting can occur in a single reactor in order to activate the sludge treatment. This Tricel solution meets the SR 66, the I.S. EN 12566 Part 3 standards and the Code of Practice 2021 (section 9 of the document). You can read more about the Tricel Novo works.

Tertiary Treatment
Tricel Novo (sewage treatment plant) + Puraflo (Packaged filter system)
or a Sand polishing filter Sandcel

A tertiary treatment system is necessary when you need a higher quality of effluents, over and above primary and secondary treatment, or for a reduction of nutrients and pathogens in sensitive areas.Based on your subsurface/surface value from your percolation test and your free draining subsoil different disposal routes can be available (section 10 of the document: Tertiary Soil Polishing Filters):

    • Option 1: Direct Discharge
    • Option 2: Pumped Discharge
    • Option 3: Gravity Discharge
    • Option 4: Low-Pressure Pipe Distribution
    • Option 5: Drip Dispersal
    • Option 6: Tertiary Treatment Systems and Infiltration Areas
      • Tertiary Sand Polishing Filters
      • Tertiary Packaged Filters
      • Constructed Wetlands Providing Tertiary Treatment

For tertiary treatment with option 6, the free-draining performance required is 0.9m, however, with proven results, this can be reduced to 0.6m.

Tricel has a wastewater treatment solution that can be used with all tertiary treatment options, as mentioned above.

Download our documentation

Have a look at the 2021 CoP

Code of practice 2021 – New T value range

Firstly, there is a terminology change, the previous ‘T-test’ is now called subsurface and ‘P-test’ is now known as surface.

The Code of Practice 2021 sets out a new range of T Value (Percolation Value) for infiltration and tertiary treatment, depending on your disposal route, as you can see below:


CoP21- Infiltration/treatment area and trench length design for tertiary treatment, per PE

The main changes are:

  • Trench length and area required are now designed per population equivalent, which makes it easier to calculate as we just need to multiply up by the number of people within the house


  • A bigger disposal area is required from 41 to 50 Percolation Values for gravity discharge – Option 3


  • The maximum allowable percolation value for domestic wastewater treatment systems discharging effluent to the ground has increased up to 120: for Low-pressure pipe distribution, option 4, a subsurface value between 3 and 90 can be used, and for Drip dispersal, option 5, a subsurface value between 3 and 120 can be used


  • The EPA’s Code of Practice has now provided new loading rates values which make the tertiary infiltration area larger, option 6

Have a look at all the changes in detail on the EPA’s Code of Practice 2021.

De-sludging recommendation

The lack of tank desludging is an issue in the wastewater industry. Not de-sludging a septic tank led to a sludge accumulation and may cause a malfunction of your system.

The 2021 Code of Practice introduced this operational change by adding a de-sludging frequency recommendation. The table beside includes a rate per annum, based on the size of the tank and the number of house occupants.

De-sludging frequency (1 to 5 years) for various sizes of tank and Number of house occupants

For example: for a 3.5m3 tank for a 3-person house, you may de-sludge your tank every 4 years.

If you do not know the size of the tank, you may use the first row of the table.

When you are de-sludging your septic tank, the pump chamber should also be de-sludged. After de-sludging the chamber, the pump unit should be hosed down, the wash water and sludge should be removed from the pump chamber, and the effluent filter should be cleaned.

You’ll find more information on the EPA’s Code of Practice 2021.

Code of practice 2021 – Site Assessor reports changes

Tricel Site Assessor

The Code of Practice 2021 also introduces a new chapter to consolidate all the site characterisation criteria regarding planning application and site assessor reports.

Tricel Site Assessor, our free wastewater site recommendation reports tool, includes the requirement of the new Code of Practice to all Site-Specific Reports.

Main changes and additions
on Tricel Site Assessor

The main changes are:

  • All old references to the CoP 2009 have now been amended to the new 2021 version.
  • All sizing references have now been updated (ex: report 2, Package Plant with Gravity Soil Polishing Filter)
  • The terminology changes ‘T-value’ to subsurface and ‘P-Value’ to the surface has been updated on our reports

Seven reports for wastewater site recommendation are available on this tool:

  1. Septic Tank with Percolation Area
  2. Package Plant with Gravity Soil Polishing Filter
  3. Package Plant with Pumped Soil Polishing Filter
  4. Package Plant with Sand Polishing Filter
  5. Septic Tank with Tricel Puraflo & Percolation Area
  6. Package Plant with Tricel Puraflo Tertiary Treatment
  7. Septic Tank with Tricel Puraflo & Soil Polishing Filter

We also plan upcoming changes:

  • New layout
  • Additional disposal routes to be added, options 4 and 5
  • Additional third-party treatment options will be available

In total, 14 reports will be available on TSA.

Choosing a Tricel’s wastewater treatment system

With Tricel you are guaranteed peace of mind through high-quality and certified products. Our range of sewage treatment plants is designed and tested to meet CE regulations and industry standards.

As one of the largest manufacturers of sewage treatment plants in Europe, Tricel is regarded by regulators as the standard setters within the industry. Our company offers innovative and leading solutions that our customers can trust.

With Tricel you are guaranteed of the following:

  • Free consultation/advice
  • High quality and certified products
  • A network of recognized and highly professional installers
  • Free commissioning
  • Maintenance and service contracts available on demand

What is PE ?

PE represents the initials of Population Equivalent. Population equivalent: conversion value which aims at expressing non-domestic applications in terms of domestic loading based on 1 person creates 60 g/day BOD5 and 150l/day. (Code of Practice: Wastewater Treatment and Disposal Systems Serving Single Houses (p.e. < 10), EPA)

Different products sold by Tricel

Tricel Novo & Vitae: Both are wastewater treament plant solutions manufactured by Tricel. Wastewater treatment plants offer a superior quality of treatment. For example, the Tricel Novo comprises of three independent wastewater treatment zones and offers an average of efficiency of 95.9% BOD removal.
This is a higher treatment standard than the effluent from a septic tank. Please note: all wastewater treatment plants used in Ireland must comply with the EN12566-3 standard and all septic tanks must comply with the EN12566-1 standard..

Tricel Vento: The septic tank from Tricel is manufactured as a primary treatment. Designed for the settlement of your effluent. This product may need an additional treatment like the Sandcel or Puraflo.


More Details

Tricel warranties

Most Tricel products have a warranty. To discover all the guarantees on our products, as well as on the internal parts, consult our dedicated product pages.

Certifications for Tricel wastewater treatment systems

The Tricel wastewater treatment plants comply with the European Standard EN12566, S.R. 66, and with the Environmental Protection Agency (EPA) Code of Practice. Click below for more details about the certifications.

Maintenance on the wastewater treatment systems

Tricel recommends that you maintain your device to the fullest. You are obliged by law to avoid all types of pollution or nuisances. Do not hesitate to contact us for more information on our service contracts. An annual maintenance contract may be offered.

Contact us

Key Features

Sandcel Sand Polishing Filter

Reliable & long-lasting

SMC tank, strong & lightweight

Sandcel Sand Polishing Filter

Fast delivery

Manufactured in Ireland, short lead time

Sandcel Sand Polishing Filter


CE certification EN12566- 3, EN12566-1 and S.R.66

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    Tricel (Killarney) Unlimited Company
    Ballyspillane Industrial Estate, Killarney, Co. Kerry, V93 X253, Ireland
    Tel: 64 663 2421