Harvesting Rainwater with Aquaponics System

[Miguel Afonso]

We all know you can capture tons of water off your roof, and more often than not there is no way to store it all. There are also factors related to the health of rainwater captured from a roof, especially as it relates to the materials that your roof is made of, and other nasties such as pollution that accumulate. Each of these problems can be greatly mitigated by coating your roof with specific approved paints and setting up a rooftop flush mechanism that delays that capture of rainwater enough for the rain clean your roof first.

The issue then is what do you do with the overflow? This is where living machines in series with an aquaponics system may come in handy. We first drop some limestone rocks at the bottom of the harvesting tank to neutralize slightly acidic rainwater. When the tank is full it overflows through a gravel filter to a reed bed and then though a bed with oxgenating aquatic plants and a few fish. From there the water enters the aquaponics system which overflows to a pond system that overflows into a couple of garden beds. 

 

Reeds and aquatic plants can be harvested for composting and/or mulching. 

 

Any suggestions?

[TCLynx]

For those with an unacceptable roof surface (asphalt shingles perhaps) is there any way to mitigate the problems with that?

 

Since my roof is asphalt shingles and I'm not currently in a position to replace it since it is still keeping the rain out just fine, here is how I'm collecting rain water.  rainsaucers™

[Miguel Afonso]

Click on this link to find out more about NSF approved Elastomeric coatings for harvesting rainwater off less than desirable roofs. I like your inventiveness TCLynx, it looks like you're having a lot of fun playing mad scientist in the backyard. Love the rainsaucers. 

[TCLynx]

Even better!  Those are out on the driveway in the front yard.

[Michael Welber]

I have just completed work on a 5000 gallon cistern for my house. I have started allowing the overflow from the flushing system run onto my native planting but using it instead for water for the aquaponics system makes good sense. It's quite a bit of water. The system you describe, however, sounds rather complex and I'm wondering if all those steps are necessary. I live in the Florida Keys so we don't get acid rain. I haven't tested the pH of the rain water but will to see how acidic it is. Our drinking water has a very high pH (9.0!) so that will not provide good water for fish or plants and I have planned to use the cistern water directly. 

So I'm wondering if the gravel filter and reed bed are truly necessary. 

[Miguel Afonso]

Rain water is typically neutral PH.  If there is a lot of CO2 in the atmosphere it will tend to the acidify the rain. An easy way to make sure your rainwater is balanced is to chuck one of those coral rocks so common where you're at into the tank. It will dissolve and balance the PH if the water for some reason is a little acidic, and will just be a rock in your tank if it isn't. If your roof is pretty pollution free and not made of toxic materials, go for it and have fun. Let me know how it is working for you. Post some photos

 

Take Care

M

[Michael Welber]

Great idea Miguel. I will let you know because I'm eager to find out myself. 

 

Will you be at the conference in Orlando? I will be attending and I'd like to meet you.

 

Michael  

[Miguel Afonso]

yep.

Drop me an email with your contact info. and I will give you a call some time.

 

[Michael Welber]

You can reach me at [e-mail] or [phone]. 

Miguel Afonso said:

yep.

Drop me an email with your contact info. and I will give you a call some time.

 

[TCLynx]

Rain water even where acid rain is not a problem will be a bit on the acid side but this isn't a bad thing as long as you can add a bit of minerals to help harden the water at least a little bit to help buffer the pH and keep it stable.  The plants will appreciate the lower pH provided you can keep it fairly stable.

[K Schreiber]

The safety of rain water has been a subject of discussion in my local permie group lately.  There's not a whole lot of info.  The EPA hasn't set standards for human safety, but I think there is a standard for aquatic safety.  Info we've managed to dig up so far:

 

http://tylertork.com/diyrainbarrels/safety.html

 

The Gold Book 1986 http://www.epa.gov/wa...
accessed 2010-01-09

The Red Book http://www.epa.gov/wa... 534 pages p210-223
(the pages are numbered by hand and do not match the page number given in the pdf reader software which was shown as page 242-256 on the system used when accessed)
accessed 2010-01-09

from the sand filter website: http://www.slowsandfi...

 

Sand filters can apparently filter out some of the contaminants.  Contaminants can come from the air as well as the shingles and it can be hard to know which is which.

[Miguel Afonso]

I really liked the slow sand filter site. Thank you for your contribution.

[larry poe]

our house has asphalt shingles. there is a HUGE cistern (8-10ft across and 12-14+ ft deep) on the south side right where I want to build the greenhouse (attached to the southside of the house). its a very old house (150ish yrs) and this was the water source before the town got municipal water (we live on 10acres at the edge of a small town). all the guttering goes to this cistern.

I have used it to water the dirt garden for many years (our sewer bill is based on water consumption so I use this instead ) must not be too toxic cause I put a few fish in there a couple years ago to eat the mosquito larva and there still alive, though I have thought of using a 55gallon drum filled with sand to filter it.

 

I am building the greenhouse out of windows and patio doors with a corrugated roof