Rainwater Catchment Guidelines

[Gray Wolf]

We just had power restored an hour ago. I have always believed in preparedness, and on the food and drinking water side we were fine, but the tank in the subdivision emptied in 24 hours after the power went out- so a few barrels of water for hygienic purposes will be in order.

The topic of water has come up several times recently.  Attached below is a very interesting study on Rainwater Catchment done by the University of Hawaii.  With all the rain the Philippines experiences some form of this should be standard equipment in every home

[JD]

Roof catchment is definitely in my plan for stately JD Manor when we build it. I've been researching gray water reuse, too but that's gone into the "If We Can" file.

Thanks for the extra info, GW.

JD


[Edited to add this: Handy site for those interested in rainwater harvesting: http://rainwaterharvesting.tamu.edu/catchment-area/ ]

[fred]

This is an interesting topic for me and one I have had to think much about lately as the place we are building has absolutely no water mains from the municipal or barangay supply.. Although we will drill a deep well,the water from it is pretty much sea water.
We have a 250 (ish) Sqr mtr flat concrete roof.
Leading up to the second level we built a concrete staircase which got me thinking about turning the void beneath it into a concrete water tank/rain collector.
Now its done,I have calculated that it will carry 5 cubic meters of rain water!! The water from it then feeds a 20 cubic meter tank that we dug in the ground.. The rain water from there is pumped back up onto from whence it came..The roof!
Actually..The roof tank where it feeds the building via gravity flow.
Everything should work good..Providing it rains!

[coleman2347]

Fred,
Thats a great idea, especially if you have a concrete flat roof,  I would just make sure that the roof is stressed for it as its about 11k lbs if full.  (using Freds 5cubic mtr. capacity) .  How do you plan on filtering or treating it?  As it rains a lot here its one of the ideas I have been toying with when I finally build my house.  In this house we have a deep well that gives fairly good water so I really dont need it here but when I finally move its on the list to incorporate into the house plans.  During Yolanda as you can expect water was one of the critical needs and most here had access to none.  The doctor down the street and I both have deep wells so we ran hoses out to the street to the blue plastic barrels for anybodys use.  Lee

[fred]

I would just make sure that the roof is stressed for it as its about 11k lbs if full

Hi Coleman..
The tank on the roof will be 2 plastic tanks that are 2 Cubic meters capacity each.. they will sit on the beams near a post so should be fine.. I realize its a lot of weight..Both tanks full of water is about 4 tonne!!

How do you plan on filtering or treating it?

The rain water will come through a 4" pipe which runs right down to floor level next to the tank exterior..This pipe has a clean out at floor level to get out any sand or stones that may be on the roof slab... there is a 4" tee at the top of the 4" pipe at top of  tank where the water goes in with a simple net filter..
As I said,this water feeds the underground tank.. From there the water is pumped out,through a canister filter to a pressure tank which fills the tanks on the roof.
Should work OK but I`ll let you know if it doesn't!

[paulgee]

We decided to drill for water, others on our sub division had done that as the water flow to houses was pretty weak. Easily done, and we never connected our house to mains water, so our water costs are minimal, and we always have a pressure tank full of water. It is certainly purer than the mains water and we will get it tested for purity when we return there later this year.

I think anything which will stop you being reliant on the generally abysmal mains water available is worth considering.

[JD]

The water in Davao is pretty good. I've had it straight from the tap on occasion with no ill effects although we always bought water during our stays.

We plan on having quite a garden so while treating the harvested water to make it potable is a possibility, we are thinking more along the lines of using it around the house.

If anyone is interested in the "first flush" idea of storing clearer water with less roof dirt/debris, this is a really good droawing of what that is: http://rainwaterharvesting.tamu.edu/files/2012/08/first-flush.jpg.

The first bit of water with (hopefully) most of the dirt, bird poop and etc. in it fills the diverter chamber. Once it's full, the flow spills over to the piping leading to the storage tank. Pretty neat idea.


JD

[fred]

The water in Davao is pretty good. I've had it straight from the tap on occasion with no ill effects although we always bought water during our stays.

We plan on having quite a garden so while treating the harvested water to make it potable is a possibility, we are thinking more along the lines of using it around the house.

If anyone is interested in the "first flush" idea of storing clearer water with less roof dirt/debris, this is a really good droawing of what that is: http://rainwaterharvesting.tamu.edu/files/2012/08/first-flush.jpg.

The first bit of water with (hopefully) most of the dirt, bird poop and etc. in it fills the diverter chamber. Once it's full, the flow spills over to the piping leading to the storage tank. Pretty neat idea.


JD

Thanks for that link.. Good illustration of what I was trying to describe in post 4!

[medic3500]

I've been drinking the water from the tap here in Quezon City for two years and have had no problems. I know it is being treated somewhere along the way to the house as you can actually smell the chlorine especially after heavy rains like we have been having. 

[JD]

Just stumbled on this tonight doing more research on RCS.

Houses, buildings soon to have rainwater catchers.

My wife's been rolling her eyes over my enthusiasm for catching that sweet, tropical rain for our planned garden but it looks like our future Mayor has signed off on it.


JD

[coleman2347]

Just stumbled on this tonight doing more research on RCS.

Houses, buildings soon to have rainwater catchers.

My wife's been rolling her eyes over my enthusiasm for catching that sweet, tropical rain for our planned garden but it looks like our future Mayor has signed off on it.


JD

I had to convince my wife that rainwater is great, and would save us money in the long run..maybe its just here in Leyte but it does not seem to be a very popular way to conserve water...which has always mystified me as it rains hard and often here...

[JD]

I guess I'll have to wait to price storage tanks and the like until we're in Davao as there's little local info online. I did some some local Mindanao newspaper photos featuring huge steel tanks but I'm not sure I want one of those.

Do you have a system, Coleman?


JD

[paulgee]

I would just make sure that the roof is stressed for it as its about 11k lbs if full

Hi Coleman..
The tank on the roof will be 2 plastic tanks that are 2 Cubic meters capacity each.. they will sit on the beams near a post so should be fine.. I realize its a lot of weight..Both tanks full of water is about 4 tonne!!

Reading the above made me think - I would bear in mind the usual build quality of houses in the Philippines when assessing it's load bearing abilities.

[FMSINC]

You can build a large under ground storage tank out of cement blocks just plaster it on both sides and use rebar in the construction, just add some chlorine to the water to keep the algae down should not be that expensive with local labor and it will last a very long time.

Tom / Roxas City

[coleman2347]

I guess I'll have to wait to price storage tanks and the like until we're in Davao as there's little local info online. I did some some local Mindanao newspaper photos featuring huge steel tanks but I'm not sure I want one of those.

Do you have a system, Coleman?


JD

No not here, here I just use deep well and city water...in the new place we are planing to put up in the province I will have all three, the roof of the House/store will be designed to funnel water into a below ground catchment system.  I can then use that to water garden etc...