home made slow sand filter

where I want to · #1 09/01/14, 01:16 PM

I was thinking about harvesting and storing rain water in the winter for use in the summer. That means catching and holding water for 6 months or so as, although there is normally lots of rain in December through April, there is virtually none in the rest of the year.
The purpose of this water would be irrigation of pasture, not household use. But I don't want to irrigate with water that has been contaminated heavily with coliform or salmonella. This would be water from the ashphalt roof and I'm thinking that after a few months of sitting there in a tank, it would be pretty rank from bird deposits on the roof- and we have a lot of ravens, wood pidgeons, and numerous other birds.
So would a slow sand filter take out enough bacteria to keep stored water clean enough for a pasture? What design would be easiest to make and use?
The other serious issue here is algea and moss. BTW I do not have enough area to make a pond.

AmericanStand · #2 09/03/14, 09:48 AM

Im thinking a shot of pool shock and keeping the tank dark would be a big help.

anniew · #3 09/03/14, 10:13 AM

Let the first flush of water in each rainfall go to the ground to wash off excessive amounts of bird stuff from the roof. then put a filter of some sort, even a t-shirt type material over the inflow pipe. the more stuff you get out at the entry point, the less any bleach/shock/etc. will need to deal with. More organic matter in the water takes more ingredient to clean it up.

jwal10 · #4 09/03/14, 10:28 AM

For pasture irrigation? Really. The same animals that are on the roof are in the pasture plus farm animals. Many pastures are watered from ponds with all that and runoff.

Yes you can make sand filters. The city water here is run through a sand filter, that and chlorine makes very good drinking water from the creek. Good sand, water in the top, out the bottom. A backflush system to a drain to clean the sand as needed. cleaned water is run back up the outflow pipe, through the sand, debri is floated out a drain channel. Filter is settled, run to drain until water quality is good enough to put back on line. There are 3, in various stages of readiness, if needed online. These are open type, gravity fed, concrete basins, there are also vessel filters, both pressure and gravity flow.

where I want to · #5 09/03/14, 10:43 AM

Quote:

Originally Posted by jwal10

For pasture irrigation? Really. The same animals that are on the roof are in the pasture plus farm animals. Many pastures are watered from ponds with all that and runoff.

Yes you can make sand filters. The city water here is run through a sand filter, that and chlorine makes very good drinking water from the creek. Good sand, water in the top, out the bottom. A backflush system to a drain to clean the sand as needed. cleaned water is run back up the outflow pipe, through the sand, debri is floated out a drain channel. Filter is settled, run to drain until water quality is good enough to put back on line. There are 3, in various stages of readiness, if needed online. These are open type, gravity fed, concrete basins, there are also vessel filters, both pressure and gravity flow.

The ravens spend a lot of time on the roof, surveying their empire. They also sit on the edge of troughs to drink, then turn around and poop in them. I sometimes really hate them. I cleaned a trough, went back to pull out the hose to fill it and the creeps had already dropped a scrap of wood in the empty trough and pooped in it.

You can harrow a slow sand filter and drain then refill to reactivate it.

The issue is the enclosed nature of a water tank to allow a small contamination to brew into a stagnant mess over the months of holding. So I'm thinking that cleaner water into the tank means acceptable levels of contaminatiin coming out. If the poop in the pastures if exposed to sun and air and periodically flushed by rain, the tank is not.

where I want to · #6 09/03/14, 10:53 AM

My trouble is I have never seen such a filter in action. There are plenty of pressure sand filters on line but no old fashion slow filters that I can find.

Nimrod · #7 09/03/14, 11:26 AM

If you store rainwater in a tank for 6 months it is likely something will grow in it even if the water was clean to start with. I suggest you fill the tank and then add however much chlorine bleach it takes to kill everything in the tank. The chlorine will evaporate through the vent so there won't be chlorine in the water after a while. Monitor the tank and add chlorine as needed.

If you filter through a piece of cloth you will keep the big pieces from going into the tank. A sand filter would probably remove the bacteria but something will grow in it during the months of storage and you will have to treat with chlorine anyway.

jwal10 · #8 09/03/14, 11:34 AM

Sand filters need to stay wet to activate the top layer that does the work. Chlorine would kill that layer. Any sand filter will plug after a while, the reason it needs back flushed....James

where I want to · #9 09/03/14, 04:18 PM

Quote:

Originally Posted by jwal10

Sand filters need to stay wet to activate the top layer that does the work. Chlorine would kill that layer. Any sand filter will plug after a while, the reason it needs back flushed....James

Sand filters are inline before the water goes to the tank. So chlorine is not an issue.
I did read that it is possible to rake up the top few inches of a sand filter the allow the water to drain out, then refikl so the active layer reforms.

where I want to · #10 09/03/14, 04:20 PM

Quote:

Originally Posted by Nimrod

If you store rainwater in a tank for 6 months it is likely something will grow in it even if the water was clean to start with. I suggest you fill the tank and then add however much chlorine bleach it takes to kill everything in the tank. The chlorine will evaporate through the vent so there won't be chlorine in the water after a while. Monitor the tank and add chlorine as needed.

If you filter through a piece of cloth you will keep the big pieces from going into the tank. A sand filter would probably remove the bacteria but something will grow in it during the months of storage and you will have to treat with chlorine anyway.

That's what I was thinking unless I could get it really clean from the get go- maybe.

Harry Chickpea · #11 09/04/14, 11:15 AM

Honestly, you are over-thinking. The birds aren't avoiding your pasture. There is not a "no fly zone" over it. You are trying to keep poo out of a manure pile.

In irrigating pasture, about the only thing I would be concerned about is keeping the pump and heads from clogging. If you spray irrigate on sunny days, you are killing a lot of pathogens simply through the process. Soil bacteria should take care of the rest in short order.

Rustaholic · #12 09/04/14, 11:54 AM

What do you have to store all this water in?

where I want to · #13 09/04/14, 12:49 PM

Two 2500 gallon poly tanks.

Honestly, when I scrub out the water troughs after a week, they can stink pretty bad. I have yet to notice a pasture stink. So I do believe that storing water can create an algae/bacteria soup that will be bad enough to create an issue if grass is watered with it. I suppose I could lock the animals in their winter dry lot and let the sun sanitize the area but that it what I'm hoping to avoid. I want minimum maintenance.

I know that any stock tank I have left in an area where the rain drips into it from the roof will get funkier a lot faster than one that doesn't.