Current Regulations

Current Regulations 2018

Building Regulations

The Building Regulations 2010 (Technical Guidance Document Part H -Drainage and Waste Water Disposal) were amended in July 2016 to make S.R. 66:2015 a legal requirement from the 1st of January 2017.
The responsibility for compliance with Irish Building Regulations rests primarily with designers, owners of homes and buildings and with builders. The amendment to take account of SR 66 is to provide structured guidelines for designers, manufacturers and plant installers. It is essential to take account of the requirements of the Building Regulations when selecting a wastewater treatment system for installation of systems up to 50 PE.
The amended building regulations are available for download at the website:

SR 66

From 1st January 2017 the new SR 66 guidance for wastewater treatment systems is a legal requirement for all systems installed of up to 50PE.
In May 2015, the National Standards Authority of Ireland (NSAI) published S.R. 66:2015 – Standard recommendation providing guidance to wastewater treatment products in compliance with the EN 12566 series of standards.
S.R. 66:2015 provides guidance on the:

1. selection of wastewater treatment plants to treat domestic wastewater for applications for populations up to 50 PE in areas without a public sewer
2. minimum performance required for wastewater treatment plants that have been tested to I.S. EN 12566 (Parts 1, 3, 4 and 6) standards and
3. scaling parameters for wastewater treatment plants that have been scaled up from the tested plant.
4. sludge storage capacity necessary to achieve the minimum performance recommended for wastewater treatment plants
5. comparability requirements for the tanks of small wastewater treatment products with shared ITT, i.e. where locally manufactured tanks are used with the permission of similar tested and certified plant owners.

S.R. 66 does not provide guidance on tertiary treatment systems.
Almost all of the requirements of SR66 refer to the certification of the septic tank or secondary treatment system to meet I.S. EN 12566 as called up in the Irish Building Regulations, and are therefore the responsibility of the tank manufacturer or supplier. As a result, the responsibility of the wastewater system designer or tank installer is primarily to ensure that the tank or treatment system is certified to meet the requirements of the Irish Building Regulations –see below. However, one situation where the system designer or installer should be aware of is the use of an existing uncertified septic tank for use with IS

EN 12566-6 e.g. an intermittent sand filter.
The wording in SR 66 is as follows:
“Where it is proposed to retain (continue to use) a septic tank, that was installed prior to the requirement to have it certified to I.S. EN 12566-1 or I.S. EN 12566-4, with a secondary treatment system certified to I.S. EN 12566-6, the septic tank to be retained should:

  • be structurally sound,
  • be watertight,
  • have a usable capacity in conformance with the EPA CoP,
  • be fitted with a suitable filter on the outlet.”

EN 12566

The I.S. EN 12566 group of standards are EU harmonised standards that provide the methodology for the laboratory testing of wastewater treatment plants in Europe. Testing includes treatment efficiency, plant structural integrity and watertightness. Plants that successfully meet the test thresholds specified by each plant manufacturer, can then be CE marked. However, CE marking is not an assurance that a plant meets the requirement of the Irish Building Regulations. A list of plants that meet the Irish Building Regulations including SR66 is available on the website of one test laboratory PIA GmBH by arrangement with the Department of the Environment: .

The “Normative” or compulsory parts of EN12566 Small wastewater treatment systems for up 50 PT are:

− I.S. EN 12566-1,– Part 1: Prefabricated septic tanks
− I.S. EN 12566-3,– Part 3: Packaged and/or site assembled domestic wastewater
treatment plants
− I.S. EN 12566-4,– Part 4: Septic tanks assembled in situ from prefabricated kits
− I.S. EN 12566-6,– Part 6: Prefabricated treatment units for septic tank effluent
− I.S. EN 12566-7,– Part 7: Prefabricated tertiary treatment unit

Parts 2 and 5 of EN12566 are “informative” or non-compulsory technical guidance documents which are considered code of practices. In reality their status is tenuous as they are in need of revision to be usable and are unlikely to be updated in the foreseeable future.

− Part 2: Soil infiltration systems
− Part 5: Pre-treated Effluent Filtration systems.

The Standard Recommendation (S.R.) was prepared by a committee of technical experts including members of the National Standards Authority of Ireland (NSAI) Wastewater Engineering Standards Committee. SR 66 should be used in conjunction with the appropriate part of the I.S. EN 12566 series and the Code of Practice entitled Wastewater Treatment and Disposal Systems Serving Single Houses (PE < 10) published by the Environmental Protection Agency in 2009 or with the Wastewater Treatment System Manual entitled Treatment systems for Small Communities, Business, Leisure Centres and Hotels, published by the Environmental Protection Agency in 1999, as appropriate.

The S.R. incorporates the National Annexes to I.S. EN 12566 Parts 1, 3 and 4 which have been withdrawn. Annex A of SR 66 summarises the required parameter values for wastewater plants to comply with SR 66. The annex A is copied in full here. The sections referenced refer to SR 66 which can be purchased from NSAI at or tel: 01 857 6730/1 or email .