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How To Filter Rainwater From Roof

Why Is Rainwater Harvesting Important

A simple filter for rooftop rainwater

Rainwater harvesting is important for several reasons but one of the biggest is the fact that we are tapping out water conservation gains inside our homes so we need to start looking outdoors for more opportunities.

The following graph shows the gains that have been achieved with our indoor water fixtures through the combination of governmental standards and innovation by fixture companies. As you can see, we dont have much more room to go in terms of achieving more efficiency gains with our indoor fixtures. Whats next the 0.2 gallon per flush toilet? Probably not!

This phenomenom is known as the law of diminishing returns. So where will the next revolution in water conservation take place? We believe we offer services in the areas where this revolution will take place.

Best Roof Material For Rainwater Collection

There are many ways to build a roof, with asphalt shingles, terracotta tiles, thatch, but none of those are suited for being used to harvest rainwater. All of them leach either chemicals or natural tannins that make the water almost impossible to filter efficiently.

Pre-painted, corrugated metal roofing is the only roofing found to be clean enough to harvest rainwater for drinking. It offers up the cleanest catchment surface possible, with little to no leaching as long as the roofing is kept in good shape.

Pairing the roofing with a galvanized steel seamless gutter will help you go even further in ensuring pristine water in your catchment tank. Seamless gutters make it possible for the water to travel freely out of the gutters and into the downspouts without any dams in between.

Plastic gutters from home depot are OK, but the do use a raised coupling to connect different gutter sections and it is there that debris, algae and pathogens tend to collect. Sure enough after the next rainfall, theyll all end up in your water tank.

To keep the roof and gutter material in good shape for continual clean water harvesting, it is advisable to pressure wash and clean out the gutters every 6 months. Before washing down the roof, make sure you disconnect the downspouts so all of that debris doesnt end up in the tank.

Layer : First Flush Diverter

Our roofs often contain a mini ecosystem of smaller contaminates such as dust, pollen, insect bodies, animal feces, or pesticides. You will need a first flush diverter to give your system a chance to rid itself of this debris. The FFD is located between the gutter guard and the tank and routes the first flow of water from the roof away from the storage tank. This first flow can be routed to a garden or planted area. I have written in more detail about how FFDs work, how to size them, and the type I prefer in my guide to rainwater harvesting.

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Best Tank Types To Store Water For Drinking

Almost any water tank will do for harvesting rainwater. All throughout East Hawaii where rainwater catchment is common practice, most people use a tank with a vinyl liner. These tanks are able to store very clean water, but there is some worry of leaching from the vinyl in some circles.

The best tank to store water would be a galvanized water tank. Galvanized metal has been tested to be very safe when it comes to the possibility of contamination through leaching. However, these tend to be very expensive. There are tradeoffs with anything.

Any water tank is better than no water tank, just make sure that it is fully enclosed or covered in some way. We still have a few filters for the water to run through before it reaches our water glass.

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Harvest And Reuse Of Rainwater From Green Roofs

How to Harvest Rainwater

Rainwater harvesting represents an alternative water supply that captures and stores rainwater for later use. The harvesting of rainwater is as simple as collecting water from surfaces on which rain falls, and subsequently storing this water for later use. Normally, water is collected from building roofs and stored in dedicated water tanks.

Green roof technology is improving all the time. The goal is to keep the water clean, in some cases probably cleaner than from some traditional roof schemes. Naturally it is necessary to observe the stability characteristics of the sub-structure, the membranes, and the related maintenance requirements.

Rainwater captured from green roofs is usually used for flushing toilets, irrigation, and for other non-potable purposes.

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Using Your Roof As The Water Funnel

If you want the easiest way to collect water, use your current roof as the way youll funnel the water directly into a barrel. This is by far the most commonly used catchment area.

Primarily because it is already equipped with gutters and other fixtures which will guide rainwater run-off into a specific direction. To ensure you get the most water run-off, its recommended you designate a downspout directly beneath a steep part of where water tends to accumulate. This will ensure you get as much rain water funneled down towards a designated location as possible.

As mentioned before about the legality of collecting rainwater, whichever decision you make, if you decide to go through with it pick an area behind or at least to the side of your home to keep your whole rainwater collection system hidden from view.

Filter To The Required Level

Filters are expensive and require replacement the more they work. A good way to keep your rainwater harvesting costs low is filtering only as much as you need to.

For instance, combining a 50-micron filter with a solar pasteurizer or another disinfection method should be good enough for your dishwashing and showering water.

Using a dedicated filter and disinfection system for your drinking and cooking water will ensure that you dont using the expensive and finer system to filter gallons of water that you will end up flushing down the drain.

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The Stages Of Rainwater Harvesting

When it comes to trapping rainwater, there numerous stages in the process. The first one is the transportation of rainwater through a system of drains and pipes. The next process is filtration and storage. Below, we explore the process of rainwater trapping in a comprehensive and easy-to-understand manner.

Different Ways To Filter Rainwater For Drinking

Rainwater Harvesting for Rooftop Rainy Filters

Filtering your rainwater into drinking water has never been easier. There are many systems out there that do a fantastic job for very little price. It was a game changer when we finally got one of our own. No more trips to the county water spigots filling up 5 gallon bottles. Drinking water now flows right out of the tap.

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Determine Where Your Water Will Go

If right at the surface, you cover with dirt to conceal them. After that place a few more cinder blocks on top to elevate your rain catching container. As you raise the container, its easier to position your container beneath the spigot where the water comes from.

We recommend you look into the Burkey Water Filtration System because it has some of the best filtering against fluoride, chlorine, lead, arsenic and much more. However, you can use any other filtering system you find suitable for your needs.

If you decide to use the water for gardening, filtration becomes unnecessary as your plants will receive the same type of rain water if you didnt collect it. You can run a hose with an electric water pump and water your garden with no further steps needed.

Why Use A Pre Filtration System

As mentioned in previous posts, rainwater itself is not dirty – your roof is though. Leaves, sticks, dirt, particles of shingles, and other contaminants all end up on your roof or in your gutters at some point. You may be thinking “so why can’t I just let debris go to the storage tank?”

Two main reasons come to mind:

  • Unfiltered biological debris in the tank provides “food” to any bacteria that may be in the water and will eventually create a very unhealthy water environment
  • Unfiltered debris builds up at a much quicker rate in the bottom of the tank and tank cleaning becomes mandatory due to this. In addition, this also tends to lead to suspended solids, more water discoloration, and last, but not least: odor. And man, does it smell!

This simple step of pre-filtration eliminates or drastically reduces all of these factors and makes system maintenance very minimal. Most of our customers only need to clean their filter screens 2-3 times per year and never have to clean their tanks. Reducing the amount and size of particulate that makes it into the tank also prolongs pumping equipment and post-tank filtration equipment by not clogging it with gunk.

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Different Methods Of Collecting Rainwater

Although the basic principle behind collecting rainwater is the same, there are some differences regarding the scale of the collection system. To know how these methods affect the degree of actual water conservation, lets take a look at them in detail.

Dry systems are usually used to store larger amounts of water, so they are often used in farms or facilities.

The Easy Way: Use Your Home Square Footage

Rooftop Rainwater harvesting in 2020

The most important key here is that the slope of your roof does not matter. While the slope can affect how many squares of shingles you might need to buy, your catchment area is essentially the amount of ground covered.

So to get a really easy estimate, use the total square footage of your home to figure out what your max potential will be for collecting rainwater. This is also really easy to get just by finding your house on Zillow.

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From Rain Gardens And Swales To Ponds And Hydroponics These Ideas Go Beyond The Basic Barrel

  • University of St Andrews
  • Harvard University Extension School

So, you’ve taken the step of diverting and collecting the rainwater that falls on your roof. This is an excellent ideahelping you make the most of this natural resource and use it more wisely on your property. But what next? Many people stop at the stage of collecting harvested rainwater in a barrel or butt. But thinking about where the water goes next can help you make the right choices for water management in your garden.

How To Purify Rainwater For Drinking

While its easy to think it could never happen to you, emergencies are something we all need to prepare for. Haunting stories like Flint, Michigans lead-poisoned water, the 2014 West Virginia chemical spill, and of course the infamous Exxon-Valdez oil spill remind us that nobody is immune. Now is a good time to think through what you might do if you suddenly couldnt drink the water that comes from your tap.

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How To Filter Rainwater From The Roof For Household Use

You can purify your water further using progressively finer filters that get rid of all solid particles and microbes to make it safe for all consumption. An extra disinfection step kills all organic components making it as safe as a municipal water supply.

Filters are rated by the smallest size particle they can capture. This is often down to microns. The finer the filter the more it can capture.

When dealing with rainwater, you should go for filters as large as 50 microns at the very start to eliminate all visible large particles that makes your water dirty and gross to the eye.

After this, you can decide on which approach to use to get rid of microbes.

  • You can use chlorination, ozonization, UV light to kill the microbes
  • Go for finer filters
  • Solar pasteurization

Rainwater Harvesting & Why Is It Essential To Your Health

How to HARVEST RAINWATER from your roof

Rainwater harvesting involves accumulating rainwater from the moment it falls from the sky to storing it to use for a later time. It can be used to water your plants, shower, or even to drink. The best way to go about doing it involves taking some sort of vessel and leaving it out when it rains. From there, it will catch all the rain that you need and you can use it however you see fit.

There are several different ways to harvest water. You can gather it as its coming out of the clouds, or you can take it from other surfaces including parking lots, roadways, and driveways.

As mentioned earlier, harvesting rainwater has dozens of benefits including the fact that you can save money on your next water bill. By using rainwater, youre not having to pay extra to water your lawn or even shower or do laundry.

Using harvested rainwater is also a great way to avoid having to depend on municipally treated water. In general, harvesting rainwater is sustainable and a great way to save money as well as the environment.

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How To Collect Rainwater: Harvesting Guide

In case you may have not known, WATER is the most abundant natural resource on planet earth. While most of it may be salt water, when it rains, it is natural, purified water which is the perfect source for consumption and a secondary source for watering your garden .

While rainwater collection may be an excellent way to save on your water bill, it actually is a much better way to consume water. Since things such as fluoride, chlorine and other chemicals are simply NOT found in rainwater. Keep in mind, a water filtration system is a highly recommended addition to ensure its safe to consume.

By collecting rainwater, youll begin to contribute towards a cleaner, more sustainable environment. NOTE: Do keep in mind that not everywhere you can legally collect rainwater , do check your local laws to ensure you wont have someone coming after you.

Rainwater Harvesting Basics: Filtering The Water Before Storage And Use

OverviewRainwater is amongst the purest water one can get distilled as it is by the sun. However, in a rainwater harvesting system, the water comes in contact with several surfaces, such as the roof or gutters. Its flow becomes possibly mixed with leaves or dust.To get water fit for use at the end of the harvesting process, apart from keeping these surfaces clean, we can filter the water before storage.

Materials required and site specification

Materials Required

  • PVC drum or ferro cement
  • Filtering material coarse jelly, smaller jelly, sand
  • Wire mesh
  • Outlet pipe for allowing filtered water to go out
  • Overflow pipe to allow excess water to flow out
  • Site Specification

    • Usually placed below vertical down pipe
    • Can also be placed adjacent to sump tank

    NoteA drum of 90 litres can filter the water of a roof area up to 100 m².

    Filtering material

    Placed at the mouth of the rainwater pipe, the filtering material can be very diverse.

    A combination of perforated aluminium box with mesh and sand or perforated plastic bottle with mesh and gravel are efficient.

    PVC drums

    • Advantages light weight, easy to transport, easy installation
    • Disadvantages cannot be kept in sun, limited capacity
    • Cost – around Rs. 600. If kept in the shade, it can last over 6 years

    Ferro cement filters

    • Advantages size can be made to suit the requirements
    • Disadvantages heavy, requires skill for construction
    • Cost – around Rs. 1700

    Stainless steel filter

    Construction technique


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    Rainwater Might Not Be Safe For Household Use Without Additional Treatment

    Before using collected rainwater for drinking, bathing, or cooking, consider whether treatment is needed to make it safe. Testing the water can determine if there are harmful germs, chemicals, or toxins in it. Water treatment options include filtration, chemical disinfection, or boiling. Filtration can remove some germs and chemicals. Treating water with chlorine or iodine kills some germs but does not remove chemicals or toxins. Boiling the water will kill germs but will not remove chemicals. Using a simple device called a first flush diverter to remove the first water that comes into the system may help avoid some of these contaminants. The amount of water that should be removed by a first flush diverter depends on the size of the roof feeding into the collection system.

    Consider adding a screen to the water inlet or emptying the rain barrel at least every 10 days to prevent mosquitoes from using the rain barrel as a breeding site.

    Some people add purchased, treated water to the rainwater they collect in their cistern. This may make the treated water less safe.

    Why Rainwater Harvesting

    How to Filter Rainwater from a Roof

    1) Conserves valuable water resources, especially in drought stricken areas

    2) Reduces dependence on and cost of municipal water services

    3) Reduces residential taxes like storm-water management fees

    4) Alternative to groundwater in areas with high total dissolved solids or contaminated aquifers

    5) Alternative to softening water

    6) Allows for recharging of groundwater resources

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    Layer : Overflow Skimmer

    Once the rainwater enters the tank, you will find an overflow skimmer to be of great benefit to your catchment system. Overflow siphons will keep your tank from overflowing and at the same time remove the lightest surface contaminates from your tank. This photo shows the particles collected in my overflow skimmer. This layer will also give you a cleaner upper water zone and nicer intake for the next layer.

    Can You Drink Rainwater

    We often think of rainwater as waste, but the opposite is actually true. You may remember from school how rain is formed, and hopefully I have remembered this correctly, it was a very long time ago. The sun evaporates water from the ground which becomes steam and rises up into the sky where it collects and forms clouds. Those clouds get over saturated and this causes rain to form. So essentially rain is distilled, purified water as it falls directly from the sky.

    Even as rainwater falls directly onto the ground and gets soaked up, it forms mineral water and is relatively safe to drink. So why do we need to filter it?

    Unfortunately as rain falls onto such things as the roof or brick paving, it picks up contaminates that make it unsafe for drinking. Nowadays we also have more air pollutants so we cant be sure what it is picking up even as it falls to the earth.

    So, if we can collect the rainwater directly from the sky before it comes into contact with anything that could contaminate it, such as the use of a rain saucer, it would be good for drinking . If you are collecting large quantities of rainwater from your entire property however, it would have most likely run over an area with nasties such as leaves and bird poop.

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