brand new video:
       
get all 177 hours of
presentations here.
  • Post Reply Bookmark Topic Watch Topic
  • New Topic

building a rainwater collection system  RSS feed

 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am new to this forum and new to designing a collection system, so I could use some help.

What I have : property at 3400 feet in the Sierra Nevada, the land I am working on is about 1" of drop every foot
I plan to install : a 2500 gallon storage tank about 100 feet from the house where I will collect water from the roof gutters. dropping the gutters to a vault at ground level at the house and trenching a line to the tank.
The water will be used to irrigate the veggie garden.

Any helpful advice would be most welcome.

Skip
 
Brian Knight
Posts: 554
Location: Asheville NC
8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Run your outlet, supply lines and all related fittings as big as possible to improve pressure.
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Vincent, that's a big tank, I use a pond to hold roof runoff water. The pond is about 150 feet from the house and uphill. A faucet installed to the bottom of the 2" PVC allows me to water the garden with the stored pond water.
2014-09-08-12.19.49.jpg
[Thumbnail for 2014-09-08-12.19.49.jpg]
2014-09-08-09.27.45.jpg
[Thumbnail for 2014-09-08-09.27.45.jpg]
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Did a few more measurements today, the plan is to run the gutters into a small vault on the corner of the house about 1 foot square. From there a 3 inch pipe will be run down to the tank about 120 feet away. Measured the elevation drop today and it was only 80" form grade at the corner of the house. I think the tank I am looking at has the fill opening closer to 88" so I will either need to lower the tank, or raise the vault it would seem. If I want to run directly from the downspouts to the tank do all seems need to be well sealed in order to get a good gravity feed?
 
brad millar
Posts: 102
Location: Menifee, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Brian Knight wrote:Run your outlet, supply lines and all related fittings as big as possible to improve pressure.

That will only change volume. Pressure is determined by head height.
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am not concerned with the pressure at this point just making sure I can fill the tank with nothing but gravity. The output of the tank will feed the garden, I may get a small solar pump to boost pressure on that side when irrigating.
 
brad millar
Posts: 102
Location: Menifee, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As long as the fill point of the tank is below the lowest point of the down spout gravity will fill the tank.
If I want to run directly from the downspouts to the tank do all seems need to be well sealed in order to get a good gravity feed?
No, they don't have to be sealed.
 
Brian Knight
Posts: 554
Location: Asheville NC
8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Wouldnt restrictions in supply lines hurt pressure?

I think you may want a pump but it would be nice to avoid it.
 
John Wolfram
Posts: 652
Location: Lafayette, Indiana
23
trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Brian Knight wrote:Wouldnt restrictions in supply lines hurt pressure?
I think you may want a pump but it would be nice to avoid it.


In a frictionless hose, the pressure at the end of the hose will be determined solely by height as Brad mentioned. However, using a long tube with a small diameter and a high viscus resistance will zap the already low pressure at the end of those.
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
My plan is to run either a 2 or 3 inch pipe down to the storage tank, I am not concerned with pressure on this side just getting the tank full by gravity feed. the tank will have a fill level of about 85 inches above grade, and is slightly upgrade from the garden. The garden will be on drip irrigation it I don't get enough pressure on that side of the system I am thinking a small solar water pump should work, any thoughts?
 
R Scott
Posts: 3351
Location: Kansas Zone 6a
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am more worried about you overwhelming the vault and fill pipe. How big is the roof and how fast does it rain (inches per hour in a heavy rain event)?

2500 gallons sounds like a lot, but it really isn't when it comes to roof runoff or irrigation needs.

Gallons catchment= square feet of roof x inches of rain per event x .623

And that is the single rain event with no reserve.

The other side of the equation is how long of a dry spell do you want to ride out and how much irrigation do you need to use. If you use 50 gallons per day, a full tank is a 50 day buffer.

 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Seeing that I am in California the dry spells are long most of late spring and all of summer. I do plan to have a bypass at the vault and another at the tank so I can redirect water when full or if I run into trouble at the vault. I am onlt capturing of part of the house I would estimate between 1800 and 2000 square feet. Should I increase the vault size? I believe average of 40 inches of rain a year.
 
R Scott
Posts: 3351
Location: Kansas Zone 6a
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
OK, you can capture roughly 2 inches of rain if the tank is empty. How much rain do you get in one event, or one rainy week?

As for the pipe, there is a rough formula here: http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/rainwater-harvesting-inforesourcesdownspout-gutter-sizing/
3" pipe does better than I remembered. I think you may be OK there.

I think you need a LOT more storage to make it all the way through the dry spell, unless you are only growing very little.

 
John Wolfram
Posts: 652
Location: Lafayette, Indiana
23
trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Weather Underground (http://www.wunderground.com/) is a good site for accessing historical weather data for your area that you can use to estimate how big of system you need. When doing your calculations, remember that you probably won't be watering for a bit after a rainstorm. Also, from an economic perspective it is usually better to rely on city/well water a few times a year than build a rainwater system with capacity that will only be used a few times a year.
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Vincent,
Flow is mostly dependent on head pressure. If your vault is at the same level as your storage, you will get very low flow. You are better off with running your spouts to a collector head, bigger spout down from there and transitioning to PVC with sediment leg high enough to develop adequate head. Then you will not lose water during heavy rains and allow you to save $ on PVC.. If you are in a freezing climate, this portion will need to be insulated. I use a larger diameter drain pipe and inject closed cell spray foam in between the 2 pipes.
At least look into a pond for all this water.
Yes, you will need to glue all PVC together, but leave an air gap between spouts and PVC.
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
The garden I am putting in is going to be quite large I would estimate 4000 square feet. We are using raised beds so actual planting area is somewhat less. I have not yet calculated the gallons per day I will need, but using a drip system I hope to be very efficient with the water. Adding additional tanks is an option if I need them.

The vault at the corner of the house is about 8' above the level that the tank will be placed.
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am finally getting ready to purchase all the piping for the connection from the vault to the tank. Another question for this forum, I am planning to also run a water line from the well down to the garden area, for when I don't have any rain water left in storage, and was planning to do this in the same trench. What are the thoughts on the type of pipe, PVC, PEX, Poly? The run will be about 150 feet. Thanks

Another challenge I could use advice on.... I was planning to run 3 inch drain pipe down to the collection tank but this type of pipe does not have a solid method for coupling there fore any back pressure will leak from the connections I need to make. Is there a better solution than using drain pipe ? Or does someone have a solid coupling method?
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Got the pea gravel pad in place for the water tank. And a look back up slope to the house where we will collect the rainwater to pipe down to the tank.
IMG_0042.JPG
[Thumbnail for IMG_0042.JPG]
IMG_0043.JPG
[Thumbnail for IMG_0043.JPG]
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
New tank in place for rain water collection
1128141150a.jpg
[Thumbnail for 1128141150a.jpg]
 
Vincent Spinale
Posts: 12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
An update, the system is in with a 2 inch pipe running from one corner of the house down to the tank at the garden. We have filled the 2500 gallon tank in just 3 rain events I now have the diverter valve open. Was very surprised at how quickly the tank filled given that we are only collecting water off of about 1 quarter of the roof area. Next I need to plumb the tank to the garden irrigation system, so far so good.
 
Weeds: because mother nature refuses to be your personal bitch. But this tiny ad is willing:
2017 Rocket Mass Heater Workshop Jamboree - 15 workshops in one event
https://permies.com/wiki/63312/permaculture-projects/Rocket-Mass-Heater-Workshop-Jamboree
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!