How to filter rainwater?
Rainwater is not drinkable when it falls from the sky. It collects in its path various bodies harmful to our health: pathogenic parasites, micro viruses, too low pH, dust, etc.
On the other hand, filtration and treatment of water will make it usable for almost everything, except for drinking , which is legally prohibited.
To understand the different stages, we will follow the path of rainwater, from the sky to our washing machine.
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First level of filtration, remove dead leaves and branches
Filter leaves from the roof
The first step is on your roof, within your gutter, with the retention of dead plants and branches that fall on your roof.
Very simple to install, place only a small grid at the top of each gutter downspout and/or along the entire length of the gutters (preferred).
It is important to be able to access it easily, because if you have a tree next to your roof, you will have to go up regularly to remove the branches and foliage.
The solution of putting a small mesh all along your installation is really preferred, because otherwise you risk having a slight water retention in your gutter.
This will encourage the development of tiger mosquitoes, or even a blockage of plants in the exterior pipes of your roof.
Filter the leaves in the middle of the gutter
If you have an overhead tank (a column, an amphora or a large cubic tank), you cannot filter at the bottom of the gutter . You must filter directly in the cylinder, using a rainwater collector. Thus, it attaches directly to the downspout.
The regendieb Pro collectors will separate dead leaves to let them fall to the bottom of the gutter and collect rainwater. This water is redirected to your overhead tank.
Filter the leaves at the bottom of the gutter
If access to your roof is impossible, you can install an open manhole at the bottom of the gutter with an integrated filter.
The latter, with small pebbles inside, will allow you to mechanically filter the rainwater and thus recover the foliage at the bottom of the descent.
It will then be easy for you to remove the accumulation of plants in that area.
Important
So, you will have understood, whether for an underground or aerial tank, put a first level of filtration to retain the leaves and branches.
Second level of filtration: how to filter in the tank?
It is located inside the water reserve. Once the water arrives in this cistern or tank, it is important to put a filter which can be different depending on the desired quality.
The filter basket to collect large particles present in rainwater
The wire baskettrant is the simplest filtration element you can find. It is installed inside your tank and allows you to collect the leaves if you have not been able to put filtration upstream. The filter basket then acts like a coffee filter.
Depending on the models, the filter basket can be either:
- Hanging from the lid
- Hanging from the riser
- Recessed in an integrated assembly
This filter basket can generally be sufficient to obtain clean rainwater (but remember that use for drinking is prohibited).
On the other hand, it will not comply with regulations regarding filtration standards.
To find out more, please see the article: Can you drink rainwater?
Example of a filter basket integrated into the tanks
- Ideal for using rainwater in the garden
- 100% recovery power
- Fine mesh grid 0.35 mm
- Filtration system integrated into the tank
- Suitable for roof areas up to 200 m²
- Connection in DN 110
The Minimax filter grid
The minimax filter grid will filter the rainwater and send the dead leaves via another pipe which will come out of the tank. This in-ground filter serves as a manhole for collecting rainwater.
It helps clean the rainwater collected in the tank. When it is full, it is automatically evacuated to the collective water network.
The Optimax filter grid with self-cleaning cleaning nozzle
It is currently one of the best grills on the market. Its shape will allow the particles to flow outside the tank while ensuring the best percentage of rainwater recovery.
The Optimax filter grid is particularly well suited to roofs less than 300 meters.
The recovery power of the Optimax filter is 95%, thanks to its triple filtration and its extremely smooth surface .
This is a major asset for achieving effective self-cleaning. It is made up of several grids as you can see in the video. If you take the professional management console offered by GRAF , you can, by pressing a button, send water to this filter grid to clean it.
Third level of filtration: after the recovery tank
The third and final step is at the exit from the container. After filtering the rainwater down the gutter or directly inside, you must send it into the house or your garden, using a pump.
To water only your garden, it is integrated into your pump or the strainer will be at the end of the suction pipe .
The strainer with the float allows the water to be pumped to the surface of the tank. Normally, this water is clear, because the impurities will have been deposited at the bottom by gravity.
If you put a pump directly in the tank, avoid placing it at the bottom.
20 micron filter to supply water to your home
Regardless of the turbidity of the water (suspended particle content), if you want to supply your toilet, your washing machine, etc., we must put a third filter before the pump.
Do not neglect this third level of filtration. It is really important to supply your house with rainwater.
This involves installing a cleanable 20 micron filter or several 5 and 20 micron filters with carbon filtration for example...
This additional level will remove all the small elements suspended in the water.
Filter cartridge necessary for water from green roofs or surrounded by trees
This 3rd level of filtration is suitable for green roofs.
In this situation, it is difficult to have clear water. It is therefore essential to use this type of filter in this case.
The water may remain slightly brown, but there will be no impurities in it.
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UV treatment station at the outlet of the rainwater tank
This last step is necessary if you plan to use the water for everyday purposes: your shower and bath, care, cleaning, work ... Remember that this is prohibited. Discover our article on the law in France.
If you have spring water, you can do it.
You can completely debacterize rainwater by passing it through a UV treatment console or a UV treatment plate.
The difference between the console and the turntable is that the console is equipped with different filters.
As rainwater can be used for drinking at the regulatory level, you must separate the networks in your home.
That is to say, you must ask your plumber to make a completely independent drinking water network to supply all the water points where you are likely to drink water.
Let's make a second plumbing network which will supply your toilets, your washing machine with rainwater directly.
Of course, if you have a rainwater harvesting project, or spring water collection , you can contact us to help you design this installation, and thus reduce your consumption of drinking water. Discover the pleasure of opening the tap and using “your” water!
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