Dual Plumbing System
Few days back, I was sitting for an interview to select a MEP engineer for site. Since we were about to the start the plumbing and the fire- fighting work, I was keen on knowing the knowledge of the person with respect to Plumbing and Fire Fighting.
My first question was always ‘What is Dual Plumbing System?’ Surprisingly 80% of the candidates failed to answer my question. I was surprised. If the MEP engineers working at site are unable to answer the question then I am sure most of the architects are not aware of it.
So on my first blog on services I thought let me explain the Dual Plumbing system. When you search google, you will get various answers. Simply put, dual plumbing system is a system in which you give two separate supply to a toilet. One for flushing and the other one for washing.
So how does the system work? Water is supplied in the water tanks either through municipal water supply or through bore well. In bigger complexes, (both in housing and commercial) there are big underground water tanks. From there, this water is treated to a level and then supplied to the overhead water tanks. From the overhead water tanks a pipeline takes this water to all the toilets. This is the water that is used in all the ablution taps and the health faucets. This is relatively cleaner water and is used for bathing, washing clothes and cleaning purpose.
When this water flows through the drain it is collected in a Sewage Treatment Plant before it gets discharged in the main sewer line. The water is treated back in this STP and the water is again reused for flushing. A separate pipeline is connected from the STP to the OH Tank wherein a separate chamber has been made for flushing water. This water is given as separate supply to all the Water Closets (WCs). The flushing water is again sent to STP before the final discharge on the main sewer line.
The recycled water from the STP is used for irrigation and cooling towers as well, other than flushing. There are various techniques available for STP water treatment, MBR (Membrane Bio Reactor) and FAB (Fluidized Aerobic Bed Reactor) to name a few. Not going too much in detail about them as it is too technical for an architect.
Dual plumbing system is nowadays almost mandatory in all big projects. The capacity of the STP is dependent on the technique used in the STP and also based on the amount of water to be recycled. Similarly the capacity of the overhead tank is also decided on the basis of the number of toilets that it is feeding. If we are able to recycle all the water from the STP, then it is called a zero discharge site.
There are many other ways to conserve water but will spend another in writing that. Till then happy flushing!!
