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Rainwater harvesting diverter - "First Flush System".


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Here is a little information for those who are considering rainwater harvesting. To keep the water that enters your storage tanks as clean as possible (for potable water), you will want a "first flush system" installed. This system takes the initial water that hits the collection area (your roof) and routes away from your storage tanks.

 

In order to make sure your roof has been washed clean of various debris, including animal feces, twigs, leaves, pollen, etc., it is recommended that you divert a minimum of 1 US gallon (~3.8 liters) of water for every 100 square feet (~9.3 square meters) of roof collection surface that you have.

 

Pipe size and length, for the diverter: 

 

3" PVC will take about 33" (~84 cm) of pipe to collect one US gallon of water.

 

4" PVC will take about 18" (~46 cm) of pipe to collect one US gallon of water. (This is the diameter I used.)

 

6" PVC will take about 8" (~20 cm) of pipe to collect one US gallon of water.

 

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At the moment, I have 20 square meters of collection area. That may not seem like much - well, it isn't, really. But, since mid October, our harvesting has completely filled 3 - 1,050 liters storage tanks. (One tank was about half full when we began, though.)

 

We are in the process of adding another 30 square meters of roof, part for a front porch and part to cover a kitchen and bath. 50 square meters of collection area is going to come in pretty handy come next rainy season. I am already looking at a 10,000 liter (~2,641 US gallons) blue polypropylene storage tank, for expansion of the system. I estimate that tank, alone, will store a one month supply of water.

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Skywalker

Good job.  It is ridiculous how little rain water harvesting takes place in SE Asia at the household level.

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SkyMan

I am already looking at a 10,000 liter (~2,641 US gallons) blue polypropylene storage tank, for expansion of the system. I estimate that tank, alone, will store a one month supply of water.

Wow! Sounds expensive. How about a cistern?

 

You know Paul, your posts and James' posts are starting to sound alike only on different subjects.

 

As for diverting a gallon of water, that will help but you still won't get it all. Maybe you should set up a distillery for drinking water since you probably will have difficulty buying bottled in your area.

 

With a cistern you could keep the draw tube off the bottom so the sinkers would stay on the bottom and the floaters would continue to float and you would draw from in between.

Edited by SkyMan
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thebob

I'd like to do this but tanks are so expensive, and our water is very cheap and reliable. I have 2 bathrooms, one in Basdiot, Moalboal and the other in Tuble, Moalboal. When one doesn't work (rarely) the other does.

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My first flush system is a 15 gallon barrel with a clamp on top.  The barrel has a perforated 3" PVC pipe in the middle, the pipe has an inverted water bottle inside. The 3" pipe is attached through the top to a collection funnel,  made from a 1 gallon plastic bucket with wire screen over the slanted cut  top.

 

As water enters the rough stuff is caught by the screen and since the top of the bucket is cut on a slant the debris screen is self cleaning. As water fills the barrel the water bottle rises, eventually sealing off the diverter. The water is then channeled through a "Y" into the storage tanks. I currently use a bank of several 55 gallon plastic barrels. 

 

The 15 gallon barrel has two garden spigots, one at the bottom and one in the middle to adjust how much water is used before shunting into the water bank. The 15 gallon barrel can also be used to water nearby plants.

 

I used my system to water my garden. Since our roof is asphalt shingles I wouldn't want to drink the water without first filtering it. Maybe my next experiment will be a "schmutzdecke" water filter.

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Wow! Sounds expensive. How about a cistern?

 

Well, they aren't cheap. Here are the prices I recently go from a local vendor:

IMG_0154.jpg

 

Odd, that I could buy two 10,000 liters tanks, cheaper than a single 20,000 liters tank. Not sure why that is. I may not have enough cash to buy the 10,000 liters tank right away. I may have to go with a smaller tank, say a 5,000 liters, or even a 3,000 liters option.

 

I had previously thought we would use up to 75 gallons per day, total. But, having stayed at the farm for two days so far, I have learned that we can get by on much less water usage.

 

 

You know Paul, your posts and James' posts are starting to sound alike only on different subjects.

 

Not sure I follow you here. Could you explain what you mean, please?

 

 

As for diverting a gallon of water, that will help but you still won't get it all. Maybe you should set up a distillery for drinking water since you probably will have difficulty buying bottled in your area.

 

Actually, TJ, I have a couple of options, both of which I am considering.

 

1. We do have 20 liter bottles of water available here. The supplier is about 6 or 7 kilometers from the house. I am considering this solely for drinking and cooking water. Although, rain water directly from the storage tanks has been used for cooking. I have eaten food cooked in this same water.

 

2. I am looking at an option using 20" filters, using 20 micron and 5 micron filters, as well as UV lighting.

 

 

With a cistern you could keep the draw tube off the bottom so the sinkers would stay on the bottom and the floaters would continue to float and you would draw from in between.

 

I can probably do that a with the existing tanks, and the poly tank I am looking into buying. 

Edited by Paul
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My first flush system is a 15 gallon barrel with a clamp on top.  The barrel has a perforated 3" PVC pipe in the middle, the pipe has an inverted water bottle inside. The 3" pipe is attached through the top to a collection funnel,  made from a 1 gallon plastic bucket with wire screen over the slanted cut  top.

 

As water enters the rough stuff is caught by the screen and since the top of the bucket is cut on a slant the debris screen is self cleaning. As water fills the barrel the water bottle rises, eventually sealing off the diverter. The water is then channeled through a "Y" into the storage tanks. I currently use a bank of several 55 gallon plastic barrels. 

 

The 15 gallon barrel has two garden spigots, one at the bottom and one in the middle to adjust how much water is used before shunting into the water bank. The 15 gallon barrel can also be used to water nearby plants.

 

I used my system to water my garden. Since our roof is asphalt shingles I wouldn't want to drink the water without first filtering it. Maybe my next experiment will be a "schmutzdecke" water filter.

 

I use a version a guy on YouTube went with. His user name is  LDSPepper. I have 2 1/2" PVC downspouts combining at a "T" then turning downward and going into the 4" PVC "diverter storage tube". At the bottom of the PVC tube, I have a 4" cap that I can easily remove to clean.

 

Anyway, since the 2 1/2" PVC has to adapt to the 4" PVC tube, I have a bell reducer that serves a great purpose. Inside the 4" tube is a 1.5 liter water bottle that floats to the top as the water fills the tube. Once full, it causes the water to divert to another "T", which takes it to the storage tanks.

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Anyway, since the 2 1/2" PVC has to adapt to the 4" PVC tube, I have a bell reducer that serves a great purpose. Inside the 4" tube is a 1.5 liter water bottle that floats to the top as the water fills the tube. Once full, it causes the water to divert to another "T", which takes it to the storage tanks.

 

Yep, I saw LDSPreppers vids also. I even bought the same screened gutter covers from Home Depot as he. My flush system is the same with the bell type reducer and water bottle float but utilizes the 15 gallon barrel instead of 4: PVC. After a long dry period a good roof flush is needed.  In that case I drain the barrel and have a 15 gallon flush. During a long rainy spell I can open the middle hose bib for a 7 gallon flush.

 

We recently bought a new house and my multi barrel system is not set up. I'm looking for those cage enclosed square containers like LDS Prepper has. More water storage in a smaller footprint. 

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SkyMan

You know Paul, your posts and James' posts are starting to sound alike only on different subjects.

Not sure I follow you here. Could you explain what you mean, please?

Just saying that between your off-grid posts and James' horticulture posts you could write the Mother Earth News. :)
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I see now. You had me lost for a bit, at first. 

 

I had just talked about this, and other alternative ways to be off grid and more self sufficient, for many years. Problem was, I never did anything about it, until now.

 

Now that I have started with it, well, it's like a drug of some sort. I can't get enough of it, TJ. It's a great experience. I just wish I had taken this step years ago. 

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I'm looking for those cage enclosed square containers like LDS Prepper has. More water storage in a smaller footprint. 

 

They are pretty nice, and reinforced (supported) by the frames. I have never seen anything like that here. However, there are, not unlike in the Philippines, many different sizes of steel and poly tanks. 

 

------------

 

One thing I like about here is, I am living in a very provincial part of the country. Not like jungle or anything of that sort, but it certainly isn't populated.

 

There are no coal fired power plants anywhere nearby, with their smoke belching towers. There are no other industrial areas in this region, that i know of either. So, the air for the rain to fall through is of good quality. 

 

The population for the entire country, is well under one-fifth of the Philippines, in the neighborhood of 15 million souls. This is another benefit. 

 

Personally, I wouldn't be able to think of a better area to collect rainwater from. The only place I could think of in the Philippines, that would be similar, would be on top of a mountain, perhaps Camotes. 

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You need a solar still for drinking water paul.

 

Gee, thanks Bob! Now, another thing to have to search for, online.Just what I need.  :D 

 

You should look at my favorites sometime. With my organization skills, it would take the CIA to decipher them all.

Edited by Paul
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ed villas

My first flush system is a 15 gallon barrel with a clamp on top.  The barrel has a perforated 3" PVC pipe in the middle, the pipe has an inverted water bottle inside. The 3" pipe is attached through the top to a collection funnel,  made from a 1 gallon plastic bucket with wire screen over the slanted cut  top.

 

As water enters the rough stuff is caught by the screen and since the top of the bucket is cut on a slant the debris screen is self cleaning. As water fills the barrel the water bottle rises, eventually sealing off the diverter. The water is then channeled through a "Y" into the storage tanks. I currently use a bank of several 55 gallon plastic barrels. 

 

The 15 gallon barrel has two garden spigots, one at the bottom and one in the middle to adjust how much water is used before shunting into the water bank. The 15 gallon barrel can also be used to water nearby plants.

 

I used my system to water my garden. Since our roof is asphalt shingles I wouldn't want to drink the water without first filtering it. Maybe my next experiment will be a "schmutzdecke" water filter.

could you show us a photo of this design/set up?

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