[IBC] Please help me understand

The garage by my new house has a gutter and downspout on one side. My IBC tanks are going to be on the other side of the garage and I will install a gutter and downspout there as well. How can I collect water from both sides of the roof?

I was thinking of connecting both sides with an underground pipe, but I'm not sure if the water will move towards and into the tanks. Right now it's really hard for me to understand the physics and waterflow.

Alternatively I could install the pipe above ground, at the same height as the tank valves, but I rather not see it. If possible... Please see my sketch and let me know what I should do.

I would make sure the supply pipes drop through the top of the IBC, not through the tank valve.
I would suggest using a leak  proof pipe from a location higher than the top of the IBC and attached to the downpipe.
So the pipe shape will be down the wall, along the ground, up the side of the IBC to the top.
Then have a 90 degrees bend, a short length of pipe to the centre and another elbow.
You may want to have a filter for leaves or dust.
You may want a first flush unit to ensure bird po and dust is not sent to the tank.

Hi Daniel, welcome to Permies!

I've done just as you show on my sugar shack.  I connected it to the outlet valve of the first IBC while the gutter from that side goes into the top of it.  I don't have a first flush diverter or anything, otherwise I'd've done what John suggests.

It looks like you live somewhere where it freezes so be sure to either have a way to drain the horizontal run or remove it for the winter.  Remember, if you drain it but snowmelt can fill it back up again, it can then freeze and break.

The run of piping from the far gutter has to be watertight to a point at least as high as the highest point of the IBC.  Ideally a foot or two higher.  So if there's water in the IBC, it will be at the same level in the pipe at the bottom of the downspout.  So in your second picture, there will be water pressure to the top of the blue mark in your downspout.  So you'd need to transition from downspout hardware to something more waterproof (like PVC) about 6' off the ground.  Water seeks its own level so when the far side roof is adding a gallon of water to the downspout it raises the level in the downspout and the water will then be pushed towards the IBC tote until the level in the downspout and the IBC tote are the same.  When that first heavy rain hits, that downspout may be higher than the IBC until the water starts moving so that's why you want it watertight for a few feet above the height of the IBC.

I hope that makes sense the way I wrote it up...

Mike Haasl wrote:
The run of piping from the far gutter has to be watertight to a point at least as high as the highest point of the IBC.  Ideally a foot or two higher.  So if there's water in the IBC, it will be at the same level in the pipe at the bottom of the downspout.  So in your second picture, there will be water pressure to the top of the blue mark in your downspout.  So you'd need to transition from downspout hardware to something more waterproof (like PVC) about 6' off the ground.  Water seeks its own level so when the far side roof is adding a gallon of water to the downspout it raises the level in the downspout and the water will then be pushed towards the IBC tote until the level in the downspout and the IBC tote are the same.  When that first heavy rain hits, that downspout may be higher than the IBC until the water starts moving so that's why you want it watertight for a few feet above the height of the IBC.

Great work getting this going! Once it is set up right, it will be a great resource for your site!

Mike is right. Water will fill to the same height in any connected containers - aside from thinner tubes, of course, where capillary action can raise the water level. This, of course, is only *after* the storm. During the storm, you will have water moving so fast that it can overwhelm a system and flow out of unimaginable places.

There is a lot I don't know about water catchment but, given the current configuration, during a heavy storm your gutter appears likely to back up unless there is an overflow that I don't see in your diagram or photograph. I could be wrong about that, of course, and there may be some detail I have overlooked. If, however, I am correct, the water will back up into your gutters, and through the seams in the downspouts, as the water gushes off the roof. You will also want to consider some sort of filter - to remove large debris, and a clean-out, to allow you to remove sludge and smaller debris from your horizontal pipe. Honestly, a 2" underground pipe seems like a bad idea to me, since it will clog easily and won't move anywhere near the volume you will have from an ordinary downspout. If you don't mind the look, you might do better to have a 3" (or even  4") CPVC pipe that runs, at a slight angle, along the side of the building - perhaps just below the windows. You could then have a clean-out at each end of the pipe and, hopefully, find a way to dump the water into the top of the IBC. A clean-out at each end of the pipe would make it a lot easier to ram a long stick, from one of the pipe to the other, to clean it out quickly and easily.

I hope this is helpful. I will trust others to correct me wherever I might have missed some important points.

Cheers!

Yes to the replies.

I'll add that I'm in the Daley thought camp that filling from the top is better (but not the only way, obviously).  That underground pipe is effectively an underground reservoir that is below the outlet from the tanks... thus it will never dry out and it may not flush out either.  So consider:
a) adding a T junction in the middle of the pipe with a drain pipe running away from the building.  Nothing fancy ... just a standard plumbing clean out that you can periodically unscrew and let it drain.
b) there's a chance that you could run the drain across the side of the building, above the windows.  Hard to tell from the photo.  You might be able to use gutter downspout... which is cheap and easy to work with.  Maybe not ... but then you have both gutters joining together so a flush/filter system is easier to install (one of them... instead of two).  Well, you could run the pipe ACROSS the windows but then you're really placing function above aesthetics and that can be hard for others to accept!

Before working on an underground piping system, I'd suggest you just install gutters on the other side and see if that is sufficient for your needs. That looks to be a rather sizeable garage, and based on the grass in the photos it looks like you live in an area with a decent amount of precipitation.

That's a great point regarding sizing.  Do a bit of math on the size of your roof vs the capacity of your tote(s).  I have 5 IBC totes getting the rain from both sides of my 14' by 34' sugar shack.  It takes about 4" of rain to fill them all up.  No sense running a more complicated piping system if the totes get full with an inch of rain (in your climate).  Better effort would be spent on getting more totes.

I would also consider running it through the inside of the garage and directly to a tote. Properly installed pvc will be no different than the plumbing in your house as far as leaks go.

Wow, I didn't expect so many replies, thanks everyone!

Based on all the feedback I changed my sketch, please see the new pictures I uploaded to my first post.

Some more info: the garage is 24 x 24 feet and we now live in Woodstock, New Brunswick (Canada). I think we get a fair amount of rain, although we only live here for 2 months and haven't seen much so far. I might consider a first flush system, I'm not sure if it's worth it.

@Mike: The winters here are long and cold (as I've been told). Curious how you know this, just by looking at this sunny picture?

@Karl: the overflow was somewhat hidden in my first sketch. I moved it in my second one so it's more clear.

@Eliot: At first I was considering to run the gutter or pipe above ground and above the windows. I didn't really want to do this because it doesn't look nice. Maybe I can paint it in the same color as the vinyl siding and I'll probably never notice it again. It's probably the best way to do this, also because of the low temperatures in the winter.

@John: that's my idea as well, to get everything ready on the left and then connect the right downspout to it all so I can collect water from both sides. I found someone who's selling a lot of IBC tanks in my town, but today I found out there were chemicals (for cars) in it. Hope I can find a way to clean them (probably not), or find another place to buy them (probably not either...).

@Don: I like the out of the box thinking of running the pipe through the inside. I will consider this, although I'm not sure if I feel comfortable doing this myself.

Daniel Benjamins wrote:@Mike: The winters here are long and cold (as I've been told). Curious how you know this, just by looking at this sunny picture?

I was assuming the picture was relatively recent (a bit of a risk) so the tulips in bloom would put you in a chillier part of the world.  Plus the grass appears to be something you're more likely to see in the North than in the South.  And there is a maple tree in the distance which I tend to associate with areas that freeze.  I'm sure there are other little details that could place your location in Canada but that's beyond me.

A couple of more thoughts;
Be careful the overflow does not syphon the tanks dry.
I have found the cost of connecting a number of IBC's together very high.
With some I purchase a submersible automatic pump instead of connections and pump the water
to a larger 22,000 Litre tank.

#2 looks to be the only good way across, barring very special circumstances. The buried pipe is work and problems bought expensively.

However. You want to be able to get the water from the gutter on the right side (in the photo) into the horizontal pipe and, here's the thing, do it in a way that doesn't "push" the horizontal too far down and "into" the windows. Depending on the _exact_ height of the gutter vs. the top of the windows, you  may NOT be able to find an elbow that will collect from the gutter and send the water horizontal w/out dropping too low. The pics make it look very close and if that is the case, you need to obtain the actual fitting you need and test it in place before making plans. That is the only reliable way to find whether it's a "close fit" or a "close miss-fit".

Running the horizontal below the windows has a lot going for it in practical terms, except: There is a close fit where you want it to clear the top of your tanks and drop in (it may end up too low at the tanks to get in over the top). However, it's a lot easier to sink the tanks 12-18" than to lower the windows!

Do research and list rainfall data for your locality. Work the numbers and see what you're going to get through those pipes. Down spouts are sized to accept certain maximum flows and in all jurisdictions that I know of it's in fact illegal to reduce the size of a drain relative to the size of it's source. It's pretty important consideration. True, nobody's likely to jail you or even give it a thought. But you might wish you gave it a _lot_ of thought if you try running a 4" downspout into a 2" drainpipe. Give your system a reasonable chance by not undersizing any parts of it. Weakest link and all that. With the price of materials, especially plastic, there really isn't much excuse not to go full size.

This stuff becomes much more important if you hope your system will survive on it's own with nobody present for weeks at a time. Design for failure, for _graceful_ failure. This means clean-outs, overflows, debris catchments or ejectors. Know where the water will go when different and varying parts of your system quit and try to ensure that will be fine over a long period which you may be absent. It means making it trivially easy to drain and/or maintain your system. Electrical parts in any plumbing system are a huge risk because equipment and electrical power are relatively unreliable. But water often simply does not stop.  Don't bet anything important on a pump working when it's supposed to. Gravity is _much_ more reliable!


Best luck,
Rufus

#2 will be very tight or quite possibly not doable with the fittings commonly available for gutter hardware.  The pic below is of a "standardish" 3" by 4" downspout elbow.  There aren't dimensions available but looking at the outlet end, it's 3" tall.  You can imagine that to the very top it would be something like 9".  You can cut off some of the unneeded upper part but I'm guessing you'd be stuck with at least 7-8" of overall height.  Assuming your siding is 4" per groove it looks like you have maybe 8" to work with.  I'm not sure what slope horizontal downspouts need but I'm guessing it's a drop of 1/2" per 10'.

What about option #7 where you run a watertight pipe above the ground in the flower bed?  Then it's not buried and easier to fiddle with.  And you have to bonus of being able to see it all the time.

Instead of squeezing a metal bend onto the downpipe, just have a stormwater plastic elbow or even a T at the start pint.
They take very little room.
By installing a Y there you may be able to have dirt trap attached.
\Evena simple one consisting of say 2 ft of storm pipe with a screwed cap glued to the bottom.
If you drill a small hole, say 3/8 " or even 1/4 inch for a start, it may trap and dispose to the ground the first flush of dust etc ioff the roof.

John's idea sounds good. There are PVC drain fittings with less "sweep" than the normal sheet metal ones. The attached pic is a short elbow to give the idea, but a tee like John suggested, would be better so you could have a clean-out up there, just in case. When EVER you use threaded plastic connections (like a clean-out with a threaded plug) use a _lot_ of teflon tape and don't (really, don't!) crank down on it super tight. Once you _carefully_ get the threads started right, a 4" PVC plug gets plenty tight with a gentle application of a pair of channel locks.


Regards,
Rufus

With the 90mm stormwater pipes and fittings, teflon tape is not needed if you use screw on caps with a washer.
They will be watertight with just a hand turn.
I use 90mm pipes for all my water catchment projects, because they are practical, affordable and easily worked with.
I use a wood saw with fine teeth to cut it and I use the green high strength solvent cement for joining the components

Thanks all. Because it's hard to find some more food grade tanks in my area I will first install the gutter and connect it to the one tank I have now. It will give me enough water to water my vegetable garden for this season. Hopefully I am able to find more tanks and connect the other gutter to them as well.

Hi
I am in Sackville NB.
I have a similar size garage.
A single IBC tote under the outlet of my garage gutter on each side of the garage mostly keeps up.
I took the down spout off and let the rain fall through air to the screened inlet of the IBC.
I lose some water to wind and splashing, but have less hassle with frozen or leaf clogged downspouts.
I would suggest separate IBC on each side, a horizontal pipe run could be an ice and leaf jam hassle.
In late fall I open the drain valve and recap the IBC.
Welcome to NB!

Like Douglas, I would have a tank on both sides if possible. I would avoid 90 degree bends in the pipes/downspouts.

A while ago I found two more IBC tanks and have finished my rainwater catchment system so far. See attached picture. This year we apparently had the biggest drought in like 70 years. I had no idea since this is our first summer here.

Let's see how much water we get next year and if I still want to connect the other gutter to my tanks.


Thanks for all your advice, all!

That looks awesome! Where did you get the pipe and fittings that you used to connect them (or really, what are they called, so I can find a local supplier)?

I got everything from Home Depot, but you should be able to find it all at your local hardware store. The material is just basic ABS and for my tanks I needed the 2-1/2" pipe, adapters and fittings.