[Lawn Lad]

I'm interested in learning more about rain water collection systems for two purposes. One, we have rain water dumping from our warehouse roof onto the ground and we're getting ready to plumb it into the storm sewer with a project this winter. But it got me thinking, can't I use this water for hydroseeding, fertilizing/weed control applications and irrigating plants we have in our holding area?

How would I size my water storage tank and what type of system would I need to build to pump water for these various needs. If anyone has experience with these I'd be interested in learning as much as possible.

As well, I could see the potential for offering this type of installation for homeowners. If anyone has installed one of these for homeowners I'd like to know more about the type of system and how effective it has been and the customer's impressions.

[agla]

I have been involved with a project where we added a 10,000 tank to collect roof runoff on a large historic house. First let me tell you that a 10,000 precast concrete septic tank is huge and not cheap (a second one is slated to be installed on the other side of the building next year). After that, it is fairly simple. You put in a smaller manhole sized tank in front of it to drop out any sediment so it does not mess up your pump. A submersible pump in the big tank can be a pretty simple sump pump. At the other end of the big tank you continue with a pipe going out to keep the drainage working when the tank is full. You just continue that pipe to a retention area or leach pits or whatever you were going to do with it.

The biggest flaw in the system is that it does not take much to use the amount of water being stored and it takes quite a bit of money and effort to put it all together. When it rains the most you tend to need the water the least.

To figure how much water you will collect, you can reference the USDA soils book for your county. It will give you the average rainfall for your area. Take the inches of rain and multiply by 0.0833. Multiply that by the square feet of roof you are draining into the tank. That give you cubic feet of water that you may collect. Multiply that by 7.5 to get the approximate gallons.

I don't know how big your hydroseeder is, but it probably will drain that tank pretty quickly. The speed in which you need to pump the water might make it necessary to have a larger expensive pump. (you could just open the tank and suck it out with a gas powered pump)

Keep in mind that if you want to irrigate 1" of water a week on a 15,000 SF lawn, you'll drain the tank in 8 days.

The question is whether it is worth the effort or not.

[Lawn Lad]

Thanks ALGA... that's a great start to figuring out the cost/benefit of doing some such system. I suppose the offsetting costs from not using city water and sewer would have to be significant engough (use the water from run off and have it rain often enough to replenish it) so that the money saved on the system can offset the installation cost. I suspect that it would take quite some time (10 years?) to offset the initial cost depending on size of tank and how much water is saved. I suppose for grins and giggles you'd have to install a water meter on the outbound side of the tank so you could quantify savings.

[JEJ]

Try a search for "rain barrel" online if you are interested in homeowner scale stormwater collection. Products range from fairly unattractive plastic drums to recycled whiskey barrels. Downspout adaptors and overflows vary with the style you choose. I have only installed one and haven't gotten any feedback from the client.

I am hoping to install a few at our home soon so if I have any info. i will post.

good luck- JEJ

[Pelican]

You'd probably want to look into the permits required and fees along that line too. If you're in a municipality, it's a safe bet the building inspector will want to be involved.