okay, so now what?

So I just caught a (clean/new) garbage can full of water. There is a rain runoff spout in my backyard. It catches water that rolls down the hill diverted away from the house (we live on a 25 degree slope... don't get me started) anyhoo, I have a full can of yellowy water. How do I purify it for drinking? I've attached a picture.

Run it through a sand filter and boil it.

Filter it to get out big things you don't want to be drinking, and boil it to kill any microbes you don't want to be drinking. As an aside, that is why tea has been such a healthful beverage over the years -- you have to boil the water to brew the tea, ensuring that there is nothing nasty living in the water.

Gotta ask.. what is the main motivation for wanting to drink it? Expense, purity, scarcity, novelty, other? Do you have a garden to use it on?

My thoughts are --
...what sort of roof was the water collected from? Is it non-toxic and non-leaching? If not, then the water may not be suitable for drinking. Materials consider acceptable per Guidelines on Rainwater Catchment Systems for Hawaii are concrete, terra cotta, slate, polycarbonate, fiberglass, enameled metal, metal painted with non-toxic paint. Not listed but safe is stainless steel and plain glass (no caulking, etc). Unacceptable is galvanized metal, anything with exposed lead or caulk, any roof with zinc, asbestos shingles, fiberglass/tar shingles, rubber, tar, asphalt, wood if treated with pesticides/fungicides. Many rooves not specifically designed for water catchment often have nails, adhesives, flashing, gutters, broken tiles, paint, and sealants that can leach dangerous chemicals into the water. I know for a fact that water caught off of fiberglass shingled roof not only tastes bad but can turn clothes an odd color when used in a washing machine. My next door neighbor has that situation and now only uses the water for his trees.
...that pipe. What's is made off? Some pipes will leach chemicals into the water too.
...that trashcan. Most plastic trashcans contain fungicides and other chemicals that leach into the water.
...why is the water colored? The water I collect is clear. It is stored in a covered catchment tank and stays clear. If I were to drink the water I catch I would adjust the pH with baking soda and sanitize it with bleach while it is in the tank. Then it would be run through a filter of some sort and then a UV lamp to make it safe for drinking. Boiling for several minutes would work but only for emergencies, in my opinion. It would be cumbersome to boil water daily and use a goodly amount of precious fuel. The UV lamps work well if the water has been correctly filtered, the lamp kept on 24 hours a day, and the bulb changed regularly. I've been drinking water treated thusly for a decade now with no I'll effects.

I'm not saying that you'll suddenly get sick drinking water collected unsafely, but over time it can be a significant problem. Such problems are seen here in Hawaii when people collect off of tarps, store water in swimming pools and trashcans, use old gutters and pipes that are not acceptable to get the water to the storage area.

I'm a big advocate of collecting rainwater. With a little attention to details, it can be fine.

To make rainwater drinkable after it has contacted a surface you have a couple of options:

1) Make a 3rd world carbon filter. Get a PVC pipe, say 2 inch diameter, about 3 feet in length. Put a rounded end cap on one end with a hole drilled in the middle of the cap. Put a filter cloth at the bottom of the cap covering the hole. Put cleaned crushed charcoal (made yourself from a biochar reactor NOT the store bought stuff) at the bottom. Fill 1/3 with biochar. Put clean sand on top of this, fill 1/3 more. The tube is now 2/3 full. Place crushed cement brick and zinc nails for the last 1/3 of the volume. Let rainwater filter through the system. This design is based off of United Nations designs for 3rd world countries needing clean water. Please do your own search for UN 3rd water world filter using charcoal, sand, and broken brick.

2) Purchase a activated carbon water filter water purifier for about $150 (with or without silver ceramic filter). Need to be replaced about every 6 months.

3) Filter through sand and cloth then kill the microorganisms in the water with: boiling, bleach, iodine tablet, chlorine tablet, UV light sterilization

The water in the picture you have pictures looks like it has collected color by passing through decaying organic material (dilute compost tea!) The pipe looks to be steel construction. I would recommend using the "dilute compost tea" captured in the barrel for watering plants. Try to collect drinkable rainwater higher in the collection system prior to contact with so many contaminating surfaces.

Brett, why the zinc nails? Everything I've read and heard at lectures about catchment water here in Hawaii warns to avoid unprotected zinc. Even our roofing screws here are stainless steel instead of galvanized. Galvanized roofing nails are not to be used for water collection here.

I checked the UN site but failed to find directions for the water filter. But I did find some other sites about water filtration for developing countries. Some interesting ideas out there.

More than half the roofs in australia are galvanized tin.....

This is the only message on the site I could find relevant to collecting rainwater off of a polycarbonate roof (on a greenhouse) for drinking purposes.  Does anyone have an actual link or experience to info regarding this? I cannot find anything saying for sure on google and don't really feel like trusting one post that specifies Hawaii.  

Su Ba wrote:My thoughts are --
...what sort of roof was the water collected from? Is it non-toxic and non-leaching? If not, then the water may not be suitable for drinking. Materials consider acceptable per Guidelines on Rainwater Catchment Systems for Hawaii are concrete, terra cotta, slate, polycarbonate, fiberglass, enameled metal, metal painted with non-toxic paint. Not listed but safe is stainless steel and plain glass (no caulking, etc). Unacceptable is galvanized metal, anything with exposed lead or caulk, any roof with zinc, asbestos shingles, fiberglass/tar shingles, rubber, tar, asphalt, wood if treated with pesticides/fungicides. Many rooves not specifically designed for water catchment often have nails, adhesives, flashing, gutters, broken tiles, paint, and sealants that can leach dangerous chemicals into the water. I know for a fact that water caught off of fiberglass shingled roof not only tastes bad but can turn clothes an odd color when used in a washing machine. My next door neighbor has that situation and now only uses the water for his trees.
...that pipe. What's is made off? Some pipes will leach chemicals into the water too.
...that trashcan. Most plastic trashcans contain fungicides and other chemicals that leach into the water.
...why is the water colored? The water I collect is clear. It is stored in a covered catchment tank and stays clear. If I were to drink the water I catch I would adjust the pH with baking soda and sanitize it with bleach while it is in the tank. Then it would be run through a filter of some sort and then a UV lamp to make it safe for drinking. Boiling for several minutes would work but only for emergencies, in my opinion. It would be cumbersome to boil water daily and use a goodly amount of precious fuel. The UV lamps work well if the water has been correctly filtered, the lamp kept on 24 hours a day, and the bulb changed regularly. I've been drinking water treated thusly for a decade now with no I'll effects.

I'm not saying that you'll suddenly get sick drinking water collected unsafely, but over time it can be a significant problem. Such problems are seen here in Hawaii when people collect off of tarps, store water in swimming pools and trashcans, use old gutters and pipes that are not acceptable to get the water to the storage area.

I'm a big advocate of collecting rainwater. With a little attention to details, it can be fine.