Back siphonage
|
| This backflow prevention device includes a valve assembly with isolation valves and strainer. |
Collins Complete Do-It-Yourself Manual was published in 1986. It was created for William Collins Sons & Co. Ltd. by Jackson Day and conceived by Jackson Day Jennings Ltd.
It defines back siphonage as: ‘The siphoning of part of a plumbing system caused by the failure of mains water pressure’.
The negative pressure (or vacuum) that results in back siphonage can happen under conditions such as a water mains break or an increased use of water for fire fighting or construction purposes. When the vacuum occurs and the supply pressure decreases, back siphonage causes the water flow (or other liquid substances) to reverse.
Back siphonage may result in contaminated water being pulled into the clean water supply. This action is referred to as backflow. Backflow can also take place due to back pressure, which can occur when there is higher pressure in the system than in its supply. This can happen in certain types of heating systems where the pressure is increased for some reason (such as thermal expansion in unvented systems).
[edit] Preventing back siphonage
Air gaps can be used to help prevent both back siphonage and backflow. An air gap is a cleared vertical space that is placed in a way that allows it to control the water supply. These gaps can be used to regulate the pressure.
An atmospheric vacuum breaker (or AVB) can be used to prevent back siphonage. It is a type of backflow prevention device that can be used in situations where it is not possible to create an air gap.
Water-using appliances must provide an acceptable degree of protection against backflow or back siphonage. These parameters are determined in BS 6280:1982 Method of vacuum (backsiphonage) test for water-using appliances. Recommendations are also proscribed under the Water Supply (Water Fittings) Regulations 1999.
[edit] Related articles on Designing Buildings
- Backflow.
- Mains water.
- Plumbing.
- Potable water.
- Siphon.
- Vacuum breaker.
- Warning pipe.
- Water consumption.
- Water Services Regulation Authority.
- Water Supply (Water Fittings) Regulations 1999.
[edit] External resources
Featured articles and news
What they are, how they work and why they are popular in many countries.
Plastic, recycling and its symbol
Student competition winning, M.C.Esher inspired Möbius strip design symbolising continuity within a finite entity.
Do you take the lead in a circular construction economy?
Help us develop and expand this wiki as a resource for academia and industry alike.
Warm Homes Plan Workforce Taskforce
Risks of undermining UK’s energy transition due to lack of electrotechnical industry representation, says ECA.
Cost Optimal Domestic Electrification CODE
Modelling retrofits only on costs that directly impact the consumer: upfront cost of equipment, energy costs and maintenance costs.
The Warm Homes Plan details released
What's new and what is not, with industry reactions.
Could AI and VR cause an increase the value of heritage?
The Orange book: 2026 Amendment 4 to BS 7671:2018
ECA welcomes IET and BSI content sign off.
How neural technologies could transform the design future
Enhancing legacy parametric engines, offering novel ways to explore solutions and generate geometry.
Key AI related terms to be aware of
With explanations from the UK government and other bodies.
From QS to further education teacher
Applying real world skills with the next generation.
A guide on how children can use LEGO to mirror real engineering processes.
Data infrastructure for next-generation materials science
Research Data Express to automate data processing and create AI-ready datasets for materials research.
Wired for the Future with ECA; powering skills and progress
ECA South Wales Business Day 2025, a day to remember.
AI for the conservation professional
A level of sophistication previously reserved for science fiction.
Biomass harvested in cycles of less than ten years.
An interview with the new CIAT President
Usman Yaqub BSc (Hons) PCIAT MFPWS.
Cost benefit model report of building safety regime in Wales
Proposed policy option costs for design and construction stage of the new building safety regime in Wales.
Do you receive our free biweekly newsletter?
If not you can sign up to receive it in your mailbox here.