Ideas for harvesting rainwater

Ideas for harvesting rainwater

We all depend on water to live, humans, animals, plants ... without it life on earth is impossible, and although it is a renewable resource, we must conscientiously care for it.

In many parts of the world, there is no access to clean water and in others, there is not even water. but unfortunately in the places that do exist, it is wasted and polluted with impunity and the energy cost of making it drinkable is unknown.

Consumption in a home is an average of 150 liters per day per person, and half is spent on using the toilet, washing machine, general cleaning and watering the plants. Yes, half of all the uses we make of water inside a house do not need drinking water.

As part of the solution to the problem, there is the possibility of collecting rainwater with simple systems, at least to save the consumption of drinking water. These systems can be perfected and convert this water, also in drinkable.

Here are some tips.

Harvest rainwater

Something very simple: when it is about to rain, place buckets, cans or bottles with funnels outdoors, if under the fall of a roof, you can collect more liters in a short time. With this water you can water your plants, wash clothes and dishes among other domestic uses.

You can also collect water from the roof. It is only necessary to have basic elements such as a drain, a conduction pipe, a storage tank and a lifting structure that allows the supply of water at low pressure. So you can reduce more than 50% of your daily water consumption if you collect rainwater.

Harvesting rainwater also helps prevent flooding by lessening the load on storm drains. If every home / building collected rainwater, together we would help mitigate the problem of flooding in large cities.


  • To avoid clogging, which, in addition to the dust that is blown by the wind, is also caused by the leaves that fall on the roofs, and the birds that also dirty it, it is necessary to use filters.
  • Use containers of clean materials, avoid for example those that have contained substances such as oil, acids, etc.
  • If you want a little more pressure, the containers should be placed high enough.
  • Keep the containers covered to prevent mosquitoes from laying their eggs.
  • Regarding the roofing material: Green roofs and patio surfaces are not suitable, because they carry too much biomass. Thatched roofs give off a lot of smell. Asphalt roofs stain the water yellow. Fiber cement (Uralita) roofs release asbestos fibers. The ideal are the roofs of clay tile, cement fiber (Eternit, Duralit, etc); metal sheets of zinc (Calamine) or concrete slabs.
  • Regarding the material of the gutters, PVC, zinc sheet or bamboo are recommended.

How much water can we harvest?

The volume of water harvested obviously depends on the area of ​​the roof and the amount of rainwater that falls. This leads us to the fact that in places with very low rainfall we would need roofs with a larger catchment area, but in many places in Latin America around 500 millimeters of rainwater falls per year.

To calculate the amount of rainwater that we can harvest, we use the following formula:

V = (L x A) x h

V = Volume of water harvested
L = Roof length
A = Roof width
h = millimeters of rainwater falling

Assuming a ceiling of 10 meters by 10 meters and an annual rainfall of only 200 millimeters (which would be equivalent to a very dry, almost desert climate), about 20,000 liters can be collected in the year, or in the period of greatest concentration of the rains, as seen when applying the formula.

V = (10m x 10m) x 200 mm
V = 100 x 200 = 20,000 liters

Assuming a family of 5 people and an average consumption of 10 liters per person / day, we have that the daily consumption would be 50 liters / family. When dividing the 20,000 liters by the 50 liters of family consumption per day, it represents us that this family can have water availability for more than a year (400 days).

Innovations in rainwater harvesting

Small technologies such as Rain Drops are eco-inventions that facilitate the harvesting of rainwater.

Designs with recycled materials such as plastic bottles are also useful when collecting water. Get to know this project of an Ekomuro:

Another way to contribute to saving water is to recycle it

Recycling used water is one of the best options to reduce costs at home, and above all, to have a sustainable consumption. By reusing gray, sewage or rain water, you save thousands of liters of drinking water per year, since we can use it for all uses in which drinking water is not essential.

There are already designs of sinks connected to the toilet cistern for the reuse of water. You can also build a simple system to reuse the water from the washing machine by placing the drain hose in a 200L bucket to which a tap or tap will be installed to remove the water as we need it.

With information from: