BS 8525-1:2010 Greywater systems. Code of practice
On-site collection and use of greywater is an alternative to public mains or private potable water supply. Greywater has a variety of non-potable water uses in the home, workplace and garden.
As greywater systems become more popular, there is a need for standardization to protect the public and to ensure that reliable systems are designed, installed and maintained.
Types of greywater systems:
Greywater systems vary significantly in their complexity and size, and can be grouped according to the type of filtration or treatment they use, as follows.
a) Direct reuse systems (no treatment)
These systems use simple devices to collect greywater from appliances and deliver it directly to the points of use, with no treatment and minimal, or no, storage, e.g. a greywater diverter valve.
b) Short retention systems
These systems apply a very basic filtration or treatment technique, such as skimming debris off the surface of the collected greywater and allowing particles to settle to the bottom of the tank. They aim to avoid odour and water quality issues by ensuring that the treated greywater is not stored for an extended period.
c) Basic physical/chemical systems
These systems use a filter to remove debris from the collected greywater prior to storage while chemical disinfectants (e.g. chlorine or bromine) are generally used to stop bacterial growth during storage.
d) Biological systems
These systems use aerobic or anaerobic bacteria to digest any unwanted organic material in the collected greywater. In the case of aerobic treatment, pumps or aquatic plants can be used to aerate the water.
e) Bio-mechanical systems
These systems, the most advanced for domestic greywater reuse, combine biological and physical treatment, e.g. removing organic matter by microbial cultures and solid material by settlement. They encourage bacterial activity by bubbling oxygen through the collected greywater.
f) Hybrid systems
These systems use a mix of the system types detailed in a) to e).
BS 8525-1 gives recommendations on the design, installation, alteration, testing and maintenance of greywater systems utilizing bathroom greywater to supply non-potable water in the UK.
It covers:
a) Systems supplying water for domestic water uses (in residential, commercial, industrial or public premises) that do not require potable water quality such as laundry, WC and urinal flushing and garden watering
b) Individual and communal systems.
It applies to retrofitting and new build.
It does not cover:
1) Systems supplying water for drinking, food preparation and cooking, dishwashing and personal hygiene
2) Direct reuse systems for external use
3) Product design for specific system components
4) The reuse of trade effluent.
Contents of BS 8525-1:
Foreword
Introduction
Scope
Normative references
Terms and definitions
Design
Installation
Water quality
Maintenance
Risk assessments
Annexes
Annex A (normative) Integrated greywater and rainwater systems
Annex B (normative) Marking and labelling
Annex C (informative) Examples of typical greywater systems with different back-up water supply arrangements
Annex D (normative) Water sampling
Bibliography
List of figures
List of tables