BACKFLOW PRESENTATION By James Szymon Cavan Alex and

BACKFLOW PRESENTATION By James, Szymon, Cavan, Alex and Tom (Team ean)

WHAT IS BACK FLOW? It is the undesirable reversal of the flow of water or mixtures of water and other undesirable substances from any source (such as used water, industrial fluids, gasses or any substance other than the intended potable water) into the distribution pipes of the potable water system.

Here is a short You. Tube clip to show you how backflow happens Https: //www. youtube. com/watch? v=Yy. Ui 4 RMb-b. A

WHY IS BACKFLOW A HEALTH RISK? Backflow is a major health issue if it happens due to a cross connection (like a hose) is submerged in dirty or contaminated water. This in turn will suck up the dirty water, bring it into the water system due to the drop in pressure and contaminate our potable water supply making the supply dangerous. So all your clean water will be filled with dirt, debris, chemicals, pathogens, human waste and dangerous chemicals!

HOW IS BACKFLOW CAUSED? Backflow is cause by the water pressure in a tank or water trough being lower than the water system's pressure so it sucks in any water close to a water dispensing device such a hose or a basin tap.

HOW CAN BACKFLOW BE PREVENTED? Backflow is stopped by a backflow prevention device which is used to protect potable water supplies from contamination or pollution due to backflow. These devices are; Ø Air gaps. Ø Atmospheric vacuum breakers. Ø Check valves. Ø Chemigation valves. Ø Double check valves. Ø Pressure vacuum breaker assemblies. Ø Reduced pressure zone devices.

AIR GAP TYPES Ø AUK 1 - It is only used in water closets only so it has no tap, its gap distance is 300 mm from the overflow on the cistern to the spill-over level of the water closet pan. Ø AUK 2 - It is used in baths and basins, the size of the tap for the bath is ¾ in BSP (British Standard Pipe) and the gap distance from the overflow point is 25 mm, whilst for the basins the size is ½ in BSP and the gap distance is 20 mm. Ø AUK 3 - It is only used in Kitchen sink bidets, the size of the tap is ½ in BSP and the gap distance is twice the bore of the pipe.

FLUID CATEGORIES Ø Level 1 - Wholesome water supplied by the undertaker and complying with the requirements made under section 67 of the Water industry Act 1991. Ø Level 2 - Change in colour, taste, aesthetic, temperature or smell. Ø Level 3 - Small health risk due to low toxicity i. e. common disinfectants, or chemical additives. Ø Level 4 - Significant heath hazard due to a certain concentration of hazardous substances i. e. chemical pesticides, herbicides or environmental organisms that pose a slight health risk. Ø Level 5 - A serious health risk due to a high concentration of toxic substances like human waste, animal remains or a small concentration of very toxic substances i. e. radioactive substances or a deadly water borne pathogen.

THANKS FOR WATCHING!!

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