Rainwater Harvesting In Apartment Complexes

Our survival revolves around water and it’s hydrating properties. A day without enough water is enough to damage your kidneys and subsequently send you into multi-organ failure. All the money, all the wealth, all the material things will cease to hold importance if the very essence that keeps us alive becomes scarce. So if there ever will be another war again, it shall be for water. And it will be lethal for our species. Rainwater harvesting is one of the efficient ways to save and reuse water.

That water needs to be conserved is not a statement that needs to be stressed upon. As responsible citizens, we’re sure that you are aware of the need to save whatever precious freshwater we have left.

Our nature has a cycle that naturally purifies the water we lose before returning it to the ground. That’s why precipitation is said to offer the purest form of natural water. So, how do we make the best use out of precipitous water?

Rainwater Harvesting 101

We’re sure you’ve all come across this term multiple times. Simply put, rainwater harvesting is a combination of steps that you take to collect water that falls to the earth as rain and preserves it for future use. The implementation may not be as simple though. This is a process with many challenges.

What Role Do Apartments Have?

Well, while every responsible human being should try to conserve water, apartment residents have a certain edge. Gated societies are often seen as a collection of people, who if strive together can achieve numerous feats. Plus the roof area or surface area on which rainwater falls is quite large when compared to individual houses/ regular buildings. So imagine the amount of water that can be collected within a gated community if all the residents put their minds into it!

If you live in a gated society, and if there aren’t measures in place already, act upon it immediately. Tasks like car washing, gardening, cleaning etc do not require pristine, pure water. Such activities can make use of harvested water which would give us enough municipality supplied freshwater for other purposes.

While the monsoons are still on and before the dry spell sets in, it would be a wise move to set up your rain water harvesting system. Work with other residents, your building manager or MCs to get started early.

How Do You Harvest Rainwater?

There are, primarily, two sources from where you can collect water.

  • Surface runoff
  • Roof top

Out of the two, the roof top version is more popular because it is easier to implement. In apartment complexes, a combination of both is the best way to maximize the amount of water collected.

If you want to create a system to harvest rainwater in your community, here’s a brief on how the system works and what its components are.

  • Catchment – This is any surface on which rainwater falls. Roof/ground/balconies it could be anything. Please note, catchments are surfaces which receive direct rainfall and not water that trickled down or was indirectly fallen upon.
  • Conduit for transportation – Pipes or drains that allow the passage of water collected on catchments to reach the storage location. There are specifications for such conduits though. Drains on rooftops require a mesh at the opening to filter out debris and the ones that collect runoff too should have the ability to prevent particulate material from mixing with the water. All pipes used in rainwater harvesting are supposed to be UV resistant.
  • First flush – There are ample pollutants and toxic agents that are suspended in the air. First showers often wash such particulate material and rain on us. This water is unsuitable for any consumption. So whatever system we set up must be capable of first discarding the initial collection and storing only the water that comes in the later showers. First flush system makes sure that water collected during the first spell is collected and taken away elsewhere and not to the main storage intended for storing rainwater. Having this system in place also acts as a way to clean the transportation pipes.
  • Filter – Not having a filter system in place is like sending out an invite to pollutants to come and contaminate your stored water. Filters remove debris, turbidity, some microorganisms and sometimes color too. A typical filter system will have the following layers, in respective order – gravel, sand and mesh filter called netlon which also forms the topmost layer of the storage tank.
  • Storage – This is a component that can’t have hard and fast criteria. The storage tank often changes properties depending on the nature, amount, and quality of rainwater that is collected.

The collected rainwater often has two uses – direct use and to replenish natural aquifers. For direct usage, the water collected in storage tanks is supplied via pipelines and then finally to faucets from where it can be drawn for use. In the second use case, the water is often used to replenish ground water reservoirs like borewells, trenches or percolation tanks.

Installing A System In Apartments

Unfortunately, this is not a system that can be built instantly. It might require money and manpower. Thankfully there are several businesses dedicated to the task of setting up rainwater harvesting system. Although the cost to set up such a system is site specific, the cost is roughly around $10,000 in an average sized gated community with most of the costs being concentrated on laying the pipes.

If you want just a rudimentary system to start with, here’s what you can do. Rooftops serve as commendable catchments. Collect water that runs off the rooftops and direct them to a storage tank with average capacity, eg approx.10k litres (this is average for a large gated community). Downpipes can be used to achieve this. As per the codes in place, downpipes or any conduit used in a rainwater harvesting system must be separate from sewage lines and must comply with certain standards. This is not that difficult to achieve.

Water can then pass through the downpipes and then through a basic filter to a tank of earlier mentioned capacity. The tank can be in the basement or a lower ground as that would ease the flow of water because gravity will come to aid. It is expected that rooftops alone can supply around 9 million litres of water annually ( this is in places where rainfall is abundant).

Another alternative, a rather primitive one would be to use vessels in each balcony to collect whatever little rain that falls there. A thin muslin cloth placed over the mouth of the vessel will act as a basic filter. This water can be used for domestic cleaning purposes.

Turn This Into A Fun Activity!

As this requires the cooperation of every resident and particularly the Managing bodies, we recommend that you turn this whole idea into a “Let’s welcome the monsoon” themed event. Shortly before the rains are expected to arrive, you can conduct discussions on the significance of collecting rainwater and on the significance of recycling water as such.

Set up a basic system or a more efficient one depending on your budget and even involve the kids to help lay out basic vessels/storage containers to collect water from open areas. Trust us the effort will pay off during dry spells when water will be scarce.

Remember what we said at the opening? Freshwater reserves on our planet are fast depleting and if you don’t act immediately at that, we’ll have the next war at our gates and this time, we’ll all suffer its consequences.

So recycle, reuse and reduce wastage of water. Until the next article, stay safe and save water. Cheers!

Learn more about Rainwater harvesting

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About the Author: Ambili Mukundan

Wordsmith in the making!