Rain water is free, harvest it and save - Daily Nation

Take advantage of the rains and harvest free water

Thursday March 29 2018

A raised tank from which water is pumped to the farm pond for drip irrigation. PHOTO| DELFHIN MUGO

A raised tank from which water is pumped to the farm pond for drip irrigation. PHOTO| DELFHIN MUGO 

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For the next one week or more Ngong resident Veronica Ndungi will not worry about water to clean, wash and bathe thanks to the pounding rains, and she will not pay a dime for it. Metered water be damned.

There are three 8,000-litre plastic tanks that collect rain water from the roof where she lives, forming part of a water harvesting system installed by the landlord. The water is then piped to all the 12 units of the three-story flat, meaning tenants rarely use metered water during the rainy season. 

“I use 200 litres of water daily in my house. I have three children including a very young one, so rain water comes in really handy.

We use the water harvested from the roof to clean, cook and wash. This saves me a lot of money,” Mr Samuel Munyiri, one of Veronica Ndungi’s neighbours told DN2.

Mr Munyiri forks out Sh1,500 for water monthly but when it rains, he says, the bill comes down tremendously as a result of switching from metered water to rain water. Ms Ndungi has also registered a significant reduction in her water bill during the rainy season. She parts with Sh800 for  water on a good month. She now makes a deliberate effort to store as much rain water as possible, as evidenced by the many jerrycans of water carefully arranged outside her house. She uses not less than seven, 20 litre jerricans (140 litres) of water.

“I have been living here for one year and I have a family of three. I like it that they harvest rain water. I don’t know if the rain water is very safe for drinking so I just use it for cleaning, washing and bathing but not drinking,” says Ms Ndungi.

The water harvesting system here has endeared her to this place so much so that she declares, matter-of-factly, “If I happen to move out of this place, availability of a water harvesting system will heavily influence my decision on where to stay next.”

Ms Claire Nasike, a campaigner at Greenpeace Africa, says while the water catchment areas may differ based on topography, individuals can create artificial water harvesting techniques such as installing gutters on their roofs to direct the rain water into a tank or a recharge pit.

In so doing households help solve the flooding menace while reducing significantly their water bills, explains Ms Nasike, as seen in the case of Mr Munyiri and his neighbour.

However, as those who are harvesting rain water during this monsoon period continue to reap the benefits, majority of people in urban areas such as Nairobi are watching as billions of litres of water drain into the Indian Ocean.

Nairobi County for instance does not have a policy that compels property developers and residents to harvest rain water. Interestingly, one of the county by-laws actually forces rain water down the drain by illegalizing water harvesting in commercial buildings!

Ms Nasike says there was need to create awareness on the value of rainwater harvesting and how to make it safe for domestic use more so in urban areas where flooding from surface runoff is rampant.

“Policies need to be put in place that compels real estate developers to ensure that houses they put up are fixed with rainwater collection systems,” she adds.

But according to Mr Michael Juma, the technical director at Extreme Renovators, a home renovation company based in Ngong Town, Kajiado County, this is easier said than done. He admits that convincing a property owner to install water harvesting systems has become the biggest nightmare experts like him have to grapple with on a daily basis yet “a simple water harvesting system such as the one at Ms Ndugi’s residence, installed by our company, costs roughly Sh280,000, and comes with benefits aplenty.” He told DN2 that much of the cost incurred went towards the purchase of water storage tanks.

“These people lose a lot. At the end of the day when you look at the amount of water draining away in your compound, and imagine what you could have done with it, you regret not having a rain water harvesting system,” says Mr Juma.


While it is easy to harvest water from rooftops using gutters and drainpipes and directing the same to a storage tank, collecting surface run-off requires a little bit more creativity. But as Mr Stanley Ngugi, an agro-pastoralist from Luseggiti in Ndeiya-Karai, Kiambu County demonstrates, it is not impossible.

Two large greenhouses welcome visitors to his homestead. The greenhouses stand adjacent to a green-netted dome-shaped structure that Mr Ngugi explains is a farm pond where all the storm water in his compound drain into. His piece of land is sloppy and the pond is strategically positioned at the foot of this and easily traps the storm water.

“I have been using storm water to grow crops in my farm since 2014. The pond has a 50-cubic-metre storage capacity. I grow cabbages, tomatoes, onions, beans and even maize on my seven-acre piece of land,” he says.

He told DN2 that he prefers greenhouse farming compared to open field, “The harvest I get from the greenhouses is not just more than what I can produce in my seven acre piece of land but also more than what you can produce from 10 acre rain-fed open land farming. Plus it is less labour-intensive.”


Before he dug the farm pond, he used to wait for the rains, sometimes to no avail. He aptly remembers a season he lost all his cabbages to the dry weather. 

With storm water to boot, Mr Ngugi says he is engaged in his farm throughout the year. But perhaps the best and profitable thing about irrigated agriculture, he says, is the ability to grow and bring to the market farm produce when there is little or none in the market.

“Once full to the brim, the farm pond can last me up to three months on drip irrigation. By the time the three months are over, the rainy season is already here again and therefore you don’t irrigate your farm anymore until the rains are over. That’s usually the time to replenish the farm pond in readiness for the dry season.”

This noble idea of collecting surface run off is what has seen Mr Ngugi succeed in farming to the point of installing two greenhouses and sinking a farm pond  to collect more surface run off.

But Mr Ngugi is a worried man. During a walk around his farm, and without directing the question to anyone in particular, he asks, “Where is the rain? Where is that rain that is killing people elsewhere?” He decries the little rainfall his area has received since it started pounding, pointing to the two farm ponds which are yet to fill up.

“For the many years that I have lived here, lack of enough rainfall and generally water shortage has been the biggest impediment to this area’s economic growth, sometime to the point of relying on relief food.

“For long, local leaders have promised to supply residents with water for irrigation from the nearby Ondiri Dam but like many a politician’s promise, that has just been about it; a promise,” says Mr Ngugi.

But the story of Ndeiya-Karai  has been fast changing since 2013. There are more than 60 farmers like Mr Ngugi working hard to feed the community and the country at large and improve their livelihoods.

This is all thanks to Kenya Rainwater Association (KRA), a local NGO, who, with the support of  African Development Bank (AfDB), initiated a project to promote rain water harvesting and management.


The aim is to improve water supply to households, food security, and environmental sustainability, in semi-arid districts of Kenya.

The story of Mr Ngugi and so many of his neighbours is proof enough of the impact rain water harvesting can have on a people.

“We cannot bury our heads in the sand and hope that climate change is not real. It’s happening and people can no longer depend on rain-fed agriculture,” says Ms Florence Chepkoech, administration and communication officer at KRA.

With a grant from AfDB, they came up with two technology packages. One was a farm pond. It is eight metres long, six metres wide and two metres deep and has a storage capacity of 50,000 litres. The other package is a large farm pond with a 250m3 capacity.

“The idea was to help farmers collect run off and use the water for farming since Ndeiya-Karai is semi-arid. The small farm pond package also came with a manual pump to lift the water to a raised supply tank from where it flows by gravity to farms.

“We were very specific about drip irrigation so as to conserve water and for this project farmers were given some drip irrigation pipes,” said Ms Chepkoech.

The small farm pond also comes with a metallic roofing structure covered with a green shade net that has the capacity to prevent evaporation by 80 per cent. Additionally, a 0.8mm thick polythene sheet dam liner is laid on the floor to prevent water seepage.  

The farm ponds are also designed in such a way that at the mouth there are two silt traps to control siltation, ensuring that all sediments and debris that come with surface run off do not enter the pond.

The green net is meant to guard against evaporation but also reduce the risk of children and farm animals falling into the pond and drowning.

But the farm pond idea is not a reserve for rural areas. Urban residents can also borrow the  idea.

“You can use the farm pond to harvest water from the roof and use it to water your flowers, grass lawn or even the kitchen garden, Ms Chepkoech explains.

The small farm pond has a 50,000 litres capacity which is equivalent to ten 5,000 litres water tanks. Considering that one such tank is going for Sh40,000 while the farm pond is just Sh105,000, a farm pond comes across as being more cost effective.





Ms Claire Nasike, a food for life campaigner at Greenpeace Africa, answers question on how urban residents can go about harvesting and using rainwater.

What should a home owner have in place to start harvesting rain water and how does one go about it?

Before harvesting any rainwater, a home owner needs to estimate the area’s rainfall potential. The rainfall potential is the surface area one has available to collect water from (typically a roof) multiplied by the annual rainfall received in that area. For instance, the rainfall potential of a roof 100 m2 in an area that receives 1,000mm of rain per year is 100m3.

One also needs to determine the right amount of storage for them. This is based on how you intend to use the water. Some of the uses include watering the garden, washing the car, flushing the toilet and, if well treated, it can be used for drinking and cooking.

Prior to harvesting rain water, a home owner also needs to determine the layout option of the rain water storage. Additionally he/she needs to think of the appropriate rain water harvesting techniques suitable for the area, based on the two aforementioned points. Determining a layout option depends on the availability of space within one’s property.

What is the value of rain water harvesting and how do you go about making the water collected safe for domestic use?

Harvesting rainwater especially in urban area minimises the surface runoff likely to cause flooding and can also significantly reduce one’s water bills.

However, rain water collected from rooftops cannot be used for drinking or cooking as some of the roof tops are made from asbestos which is a hazardous material.

Before drinking or cooking with rainwater, the following precautions need to be put in place:

  •  Check the material the roofing is made from.

  •  Remove any contaminants before collecting water in the storage tank.

  •  Have pre-filtration devices in the conveyance system