Rain Barrel Plumbing - Any fluid engineers in the house?

[salty_monk]

I have a plan to connect a rain barrel to one of our spouts. I will also likely have condensate from a dehumidifier running into it too through the top (mostly inconsequential as even on a really bad day it would be less than 3 Gallons).

I think that my illustration is correct but I wanted to be sure... as the source "Gutter connect" is a good 3 feet higher than the top of the barrel I think that it will always fill the barrel & use the overflow when full and when rain is flowing (pipework is 3/4" schedule 40) even though it will have the water pressure from the 25 gallons+ sitting above the pipe connection at the barrel. Once the rain stops the pipe will backfill to where I've marked in Green I guess?

If the 3/4 pipe can't cope with the volume of water (unlikely from what I've seen from my other one of these barrels) then there is a secondary overflow at the downspout which will automatically re-direct water away down the usual path onto the yard.

I just wanted to double check my thinking before I go to all the hassle to do this. There are definitely "less hassle" ways to do what I want to do with this but doing it this way will give me some other advantages that I won't bother going into here. The reason I can't make the connection higher up on the barrel is due to placement of a window.

Thoughts please

Rain barrel by salty_monk, on Flickr

 

[Who Dat?]

Is the purpose of the barrel just to control (delay) the surge?

To get an idea of how much water might be involved, you will need to know the square footage of collection on the roof (viewed from straight overhead, not perpendicular to the roof plane) and the amount of rainfall. Knowing how many inches of rain and the collection area, you can calculate the number of gallons. The amount might suprise you. And, if the inflow from the gutter exceeds the outflow at the overflow, the level will go above your "max fill" line, probably going all the way up the downspout and overflowing from the gutter.

By your drawing, you will end up with close to 50 gallons, which may stagnate before it evaporates, unless there is some method of draining it near the bottom of the barrel.

 

[MikeLyon]

Probably not answer you were looking for, but over the years the show " this old house " has covered the whole rain barrel project many times.

Maybe you could look that up for any ideas ?

There are other videos from them on rain barrel projects.

 

[rphillips]

Way too complicated... In my early yrs. appx. half the houses and a tank, appx. 500 gal., wood or metal sitting by the house. Gutter ran into opening on top of tank, when tank was full, overflow was same opening the gutter ran into, water just ran out. faucet on bottom to get water out....Don't get much simpler and worked just fine and met all codes. Thinking you may have a more modern, more complicated, and more to "todays" codes idea. Good luck.

 

[tlg1100]

Got two neighbors that collect rain water, one using for his legal pot growing shed , the other one not sure what he's doing with it if anything

He's got a lean to style building with two plastic 55 gallon barrels underneath the downspout, about as simple as it gets

 

[salty_monk]

Is the purpose of the barrel just to control (delay) the surge?

To get an idea of how much water might be involved, you will need to know the square footage of collection on the roof (viewed from straight overhead, not perpendicular to the roof plane) and the amount of rainfall. Knowing how many inches of rain and the collection area, you can calculate the number of gallons. The amount might suprise you. And, if the inflow from the gutter exceeds the outflow at the overflow, the level will go above your "max fill" line, probably going all the way up the downspout and overflowing from the gutter.

By your drawing, you will end up with close to 50 gallons, which may stagnate before it evaporates, unless there is some method of draining it near the bottom of the barrel.

We don't get a lot of rain here..... but sometimes when it does there's a lot. Yes, essentially to your surge question and the overflow will let me move some water elsewhere when it does rain.
It's sealed and has a drain from the bottom (to use it to water plants later) so I'm not worried about stagnation and there is a re-direct on the down spout so if it ever reached there then there then it would flow down the downspout as it used to.....

I have a similar system on another downspout, it takes from half a garage and the roof over my office (so probably about 400 sq ft at ground level) and can fill that 50 gallons in a couple of hours easy when it pours. That one I can take the water off the downspout at the height of the top of the barrel so obviously it fills to the top....

https://www.homedepot.com/p/EarthMinded-Flexifit-Diverter-Upgrade-for-3-in-x-4-in-Rectangular-Downspouts-F-RN094/301326310?source=shoppingads&locale=en-US&pla&mtc=SHOPPING-BF-CDP-GGL-D28O-028_009_PLANTERS-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NA-PMAXONECLICK&cm_mmc=SHOPPING-BF-CDP-GGL-D28O-028_009_PLANTERS-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NA-PMAXONECLICK-20410374420--&gad_source=1&gclid=EAIaIQobChMIiYjzlcm_jAMVKihECB 3VKy2HEAQYAiABEgJ3svD_BwE&gclsrc=aw.ds

So as long as this layout will allow the barrel to fill to the top that should work the way I think it will.

 

[Cipher]

We don't get a lot of rain here..... but sometimes when it does there's a lot. Yes, essentially to your surge question and the overflow will let me move some water elsewhere when it does rain.
It's sealed and has a drain from the bottom (to use it to water plants later) so I'm not worried about stagnation and there is a re-direct on the down spout so if it ever reached there then there then it would flow down the downspout as it used to.....

I have a similar system on another downspout, it takes from half a garage and the roof over my office (so probably about 400 sq ft at ground level) and can fill that 50 gallons in a couple of hours easy when it pours. That one I can take the water off the downspout at the height of the top of the barrel so obviously it fills to the top....

https://www.homedepot.com/p/EarthMinded-Flexifit-Diverter-Upgrade-for-3-in-x-4-in-Rectangular-Downspouts-F-RN094/301326310?source=shoppingads&locale=en-US&pla&mtc=SHOPPING-BF-CDP-GGL-D28O-028_009_PLANTERS-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NA-PMAXONECLICK&cm_mmc=SHOPPING-BF-CDP-GGL-D28O-028_009_PLANTERS-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NA-PMAXONECLICK-20410374420--&gad_source=1&gclid=EAIaIQobChMIiYjzlcm_jAMVKihECB 3VKy2HEAQYAiABEgJ3svD_BwE&gclsrc=aw.ds

So as long as this layout will allow the barrel to fill to the top that should work the way I think it will.

The interweb says 2 inches per hour on 400 sq feet yields 8.3074 g per minute
2 is violent heavy rain, how high is the water mama? The levee is gonna break deluge
3/4 pipe can drain 11 gpm 1 1/2 35gpm

your quoted scenario is 0.41666666666 gpm

 

[salty_monk]

Yeah that would be a lot of rain for here! If we get 2” in 24 hours that would be a lot!

I don’t see an issue where it wouldn’t be able to cope but the redirect would deal with it anyway so the gutter wouldn’t overflow.

thanks for doing the sums!

 

[Grimly]

Avoiding stagnation might be of importance.

 

[Redman]

Dan,

We have one (our son made it for us from a trash can). We use it to hold water that then use for watering plants around the yard. Has hose spigit near bottom.

Per your sketch, with downspout connected in middle of the barrel, then that downspout connection to the barrel (and the downspout elbow and such) will all need to be water tight if you want the level in the barrel to ever be above that connection. Maybe have that connection near the top, or go right thru the top.

Ours doesnt have downspout piping, dont have eaves troughs. THe barrell/can just sits under the eaves at a valley, and the lid is inverted (so curves down) and has a screen over an opening. THe screen is to strain out leaves and such.

.

 

[LAB3]

Avoiding stagnation might be of importance.

Yeah, you don't want a mosquito motel in your back yard.

 

[Buffalo Bill]

Whatever your end use is, you may drop a small pump in there.
I sometimes drop a portable sump pump with a garden hose attached into my rain barrels for watering my raised beds.
Sometimes in a hot dry spell the barrel water becomes anaerobic, so ​I drop the pump in without the hose, just to circulate the water for oxygenation.
Anaerobic bacteria on leafy vegetables is bad for digestion.

 

[salty_monk]

Yes the two lower spigot connections are water tight. I have taps on them. I guess in their ordinary setup they provide two different connections for draining/using the water.
It works pretty good.
Stagnation isn’t an issue because the barrel is sealed, the mozzies can’t get in….

 

[Grimly]

Stagnation isn’t an issue because the barrel is sealed, the mozzies can’t get in….

Bird poop, algae, mosses can though, as it's fed from the roof.

 

[salty_monk]

You’re right but I haven’t seen evidence of that in my other one.

been running it over a a year now so you’d have thought it would have showed up. Maybe the diverter helps to flush any of that stuff down the downspout instead of into the barrel or maybe because it’s so dry between rain events here that stops any growth..