My idea for a rainwater catchment in the woods....

The idea here is for a rainwater catchment system that fills up a buried cistern, entirely on it's own; but is separated from the house. (I have city water, so I don't need a catchment system at the house)

I have, in the past, built a "shady pavilion" using a decommissioned parachute.  These tend to be pretty cheap overall, and the one I had was 28 feet wide. It worked okay as a pavilion, but I noticed that it worked very well at funneling rainwater; so this is my idea...

Instead of the parachute mounted with a single pole in the middle to make a pavilion, I'd use 6 smaller poles at the six corners of the parachute; or maybe just tree straps.  At the center of the parachute is a small 'vent' that's designed to keep the parachute from 'oscillating' during a decent. I'd add a few tie-strings to this hole, in order to attach a removable "sock" style filter. Directly beneath this sock filter, I would put a plastic 55 gallon drum.  Instead of a top, this 55 gallon drum would be covered by a fine screen, hopefully stainless steel.  (This is to keep out critters)  Inside the drum, it would be about two-thirds full of sand; in order to create a sand filter with a surge space.  There would have to be some kind of drain added to the drum to allow the trickle-filtered water to empty into the cistern.  The cistern does what cisterns are designed to do; keep out critters and keep cool enough that the water doesn't evaporate.  A hand pump would be all that's necessary to get the water back out when needed.  I'd likely add a one-ounce silver coin to the water, to suppress single celled growth.

Anyone have thoughts about what I'm overlooking, or how this might be improved?

I do something like this with a blue tarp.
In my case there is a 3 gallon barrel of sand set into the top of the barrel as the filter itself.
The barrel has both a tap and water nipple for the chooks.

William Bronson wrote: I do something like this with a blue tarp.
In my case there is a 3 gallon barrel of sand set into the top of the barrel as the filter itself.
The barrel has both a tap and water nipple for the chooks.

This would definitely be a cheaper option.  What do you use the water for? Irrigation or human consumption? Does it freeze in winter?  My goal here is for potential human consumption, as a pre-cursor to an "off-grid" cabin in our woods. I really don't have to irrigate in Kentucky anymore; between the climate being 3 times wetter here than in Montana and using some of the hugelcultre techniques and small swales.  So this rainwater catchment system would be set up in the woods, just so that there will be plenty of water for the cabin that comes later.

I use mine in the garden and for the chickens.
I haven't been through a winter with it yet.

Do you have the in ground tank already?
I have found that large volume water storage can be a real expense.

William Bronson wrote:I
Do you have the in ground tank already?
I have found that large volume water storage can be a real expense.

No tank yet, still in the thinking phase. I want this to be as 'out of sight & out of mind' as humanly possible when it's built.  Ideally, all you'd be able to see is an old parachute hung up in the woods; and I'd come back to it later when I want to build the cabin (or wofati) and re-locate the siphon cap.  So that by the time I actually need the water, it'd be quite full by passive rainfall collection.

Something I've thought about for an in ground tank is a pond,  with liner,  filled in with open ended containers.
The containers could be buckets,barrels , bottles,  pipes, totes,  anything as long as it can fill and drain freely.
Cover them with a tarp and cover the tarp with soil.

William Bronson wrote: Something I've thought about for an in ground tank is a pond,  with liner,  filled in with open ended containers.
The containers could be buckets,barrels , bottles,  pipes, totes,  anything as long as it can fill and drain freely.
Cover them with a tarp and cover the tarp with soil.

Hmm, good idea.  Or just a pond liner in a hole, then mostly filled back up with sand.  Maybe a depression or swale to slow down the runnoff, and a shallow well hand pump straight up the middle.

This would be a great way to do it, for those in the Western US States that get a bit weird about manmade ponds.

The top 12 inches or so could still be topsoil, seeded with water loving herbs, etc.

Water quality would be fine for gardening, at least as long as we knew where the runnoff was coming from.  I probably wouldn't use this water as drinking water, except in an emergency; and I'd still filter and boil it first.