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Written by Deb Kingsbury
Living on a 36-acre off-grid property in northern Arizona, Deb and her husband Jeremy embrace sustainable living through solar power, rainwater harvesting, and a passive solar home built with recycled polystyrene block. A freelance writer and editor, Deb grows food in raised beds and a greenhouse and is an avid hiker and backpacker. A long-time search & rescue volunteer, she has published two novels and previously homesteaded on the East Coast.
Collecting and filtering rainwater is a sustainable practice that can significantly reduce your dependence on external water sources. With a few simple, cost-effective do-it-yourself (DIY) methods, you can help ensure your harvested rainwater is clean and safe for various household uses.
Here are some practical steps to help you set up an effective rainwater filtration system.
1. First Flush Diverter
First-flush diverters, also called roof washers, are essential for any rainwater harvesting system. Their main purpose is to redirect the initial flow of rainwater, which typically contains roof contaminants like dirt, leaves, insects, and bird droppings.
Materials Needed:
Vertical PVC Drain Pipe - This will be the main body of the diverter.
Plain T PVC Pipe Fitting - To connect the drain pipe to the rest of the system.
90 Degree PVC Pipe Fitting - To direct the flow of water.
Threaded PVC Access Coupling - For easy access and maintenance.
Threaded PVC Cap with O-Ring or Ball Valve - To seal the bottom of the diverter.
Floating Ball - This ball is placed inside the diverter chamber. As the first flush of water fills the chamber, the ball rises with the water level.
Ball Seat - Once the chamber is full, the ball seats itself at the top of the chamber, preventing any more water from entering the diverter. This ensures that only the cleaner water flows into the main storage tank.
Non-Pressure PVC Cement (Glue) - To secure all the fittings together.
OR, you can purchase a first flush diverter kit with all the parts and pieces and just add the vertical pipe. This first flush diverter has a slow-release valve that automatically drains the chamber while in use, keeping it ready for the next rainfall.
To install a DIY first flush diverter, you need to set up a T-junction in your downspout. Attach a vertical pipe with a removable end cap or ball valve to this junction. As rain fills the pipe, the ball rises and eventually seals it, allowing cleaner water to pass through into your storage tank. This simple setup ensures that the dirtiest water is diverted away from your clean water supply.
Here's a good how-to video about building your own DIY first-flush diverter...
2. Sand and Gravel Filter
A sand and gravel filter is an excellent method for removing larger particles and sediments from your collected rainwater. It’s a straightforward system that you can set up with readily available materials.
Materials Needed:
Large container
Coarse gravel
Fine gravel
Sand
Spigot
Container Selection:
For the large container, you can use a food-grade plastic barrel or bucket or a large plastic storage bin. These containers are durable, easy to clean, and readily available. Make sure the container is large enough to hold the layers of gravel and sand and has a lid to prevent contamination. Another option is a food-grade bucket with a spigot already included. Setting Up the Filter:
Drill a hole near the bottom of the container for the outlet. Attach a spigot or faucet to this hole to allow easy access to the filtered water.
Layering: Start with a layer of coarse gravel at the bottom, followed by a layer of fine gravel, and finally, a top layer of sand. The layers should be thick enough to effectively filter the water but leave enough space for the water to flow through.
Using the Filter:
Pour the collected rainwater into the top of the filter.
The water will pass through the sand and gravel layers, which will trap and remove debris and larger particles.
The filtered water will collect at the bottom of the container and can be accessed through the spigot.
3. Charcoal Filter
Charcoal filters are known for their ability to adsorb odors, chemicals, and various impurities, significantly improving the taste and quality of your rainwater. You can either buy activated charcoal or make your own by heating regular charcoal.
Materials Needed:
Activated charcoal or regular charcoal
Container with mesh bottom
Container to catch filtered water
Container Selection:
For the container with a mesh bottom, you can use a stainless steel colander or a plastic colander. These containers are designed to allow water to pass through while holding the charcoal in place. Ensure the mesh is fine enough to prevent the charcoal from falling through but still allow water to flow freely.
Setting Up the Filter:
Place the charcoal in the colander.
Position the colander over a larger container to catch the filtered water.
Pour the collected rainwater through the charcoal layer in the colander.
The water will pass through the charcoal, which will adsorb impurities and improve the water’s quality.
4. Simple Solar Still
A simple solar still is an effective DIY method that uses solar energy to distill water, removing impurities and pathogens. This method might be a bit more labor-intensive, but is worth the effort for the purity of the water it produces.
Materials Needed:
Shovel
Clear plastic sheet
Small container
Small rock
To build a solar still, dig a pit and place a container at its center. Cover the pit with clear plastic, making sure it slopes toward the container. Place a small rock on the plastic above the container to create a drip point for condensation.
As the sun heats the pit, water evaporates, condenses on the plastic, and drips into the container, leaving contaminants behind.
5. Ceramic Filters
Ceramic filters are highly effective at filtering out bacteria and fine particles from your rainwater. They are simple to use and require minimal maintenance.
Materials Needed:
Ceramic filter (This is a ceramic bucket water filter kit)
Bucket or container
To set up a ceramic filter, place it in a bucket or another container. Pour the rainwater through the ceramic filter and allow it to pass through slowly. The porous nature of the ceramic material traps bacteria and other small particles, providing you with clean, safe water for household use.
Potable Rainwater Storage
Proper storage of your filtered rainwater is crucial to maintain its quality and prevent contamination. Using food-grade barrels or tanks is highly recommended for this purpose.
Ensure your storage containers are always covered to keep out debris and insects.
Additionally, use a rain barrel screen at the water inlet or mesh cover to further prevent any unwanted particles from entering the storage tank. Keeping your storage containers clean and covered will help maintain the quality of your harvested rainwater over time.
Maintenance Tips
Regular maintenance is essential to ensure the efficiency of your rainwater filtration system. Here are some tips to keep your system running smoothly:
Clean your gutters and downspouts regularly to prevent clogging and contamination.
Use downspout gutter guards and leaf filters.
Replace filter materials periodically to maintain their effectiveness.
Test the quality of your water occasionally to ensure it meets your needs and is safe for use.
Ensuring Clean Water with DIY Rainwater Filtration
Setting up a DIY rainwater filtration system doesn't have to be expensive or complicated. With a bit of effort and some basic materials, you can create an effective system that provides clean water for your household. Embrace these cost-effective methods, and you'll be well on your way to a more sustainable and self-sufficient lifestyle.
Rainwater Filtering FAQs
1. Why is it important to use a first flush diverter in a rainwater harvesting system?
A first flush diverter is crucial because it redirects the initial flow of rainwater, which often contains contaminants like dirt, leaves, and bird droppings from the roof. By diverting this dirty water, you ensure that cleaner water enters your storage tank.
2. How do sand and gravel filters remove particles from rainwater?
Sand and gravel filters create layers of coarse gravel, fine gravel, and sand inside a container. As rainwater passes through these layers, larger particles and sediments are trapped, resulting in cleaner water.
3. What are the benefits of using a charcoal filter in rainwater filtration?
Charcoal filters effectively absorb odors, chemicals, and various impurities from rainwater. This significantly improves the taste and quality of the water, making it more suitable for household use.
4. How does a simple solar still purify rainwater?
A simple solar still uses solar energy to distill water. The still removes impurities and pathogens by evaporating water and then condensing it. The process involves digging a pit, placing a container at the center, covering it with clear plastic, and allowing condensation to drip into the container.
5. What are the key maintenance tips for a DIY rainwater filtration system?
To maintain an efficient rainwater filtration system, you should regularly clean gutters and downspouts, replace filter materials periodically, and test the quality of your water occasionally. These steps ensure that your system continues to provide clean and safe water.
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