Rainwater tank flooding concerns

[Fifth]

I have a soon to be rented out property with a rainwater tank behind the garage. The garage roof gutters run into the tank. This water is only for gardening, washing cars, etc. and is not connected to the house.

The problem is, if the tenants don't occasionally use the water, the tank will overflow, flooding the garage. By flooding, I mean a very minor flood. Still, in our overly litigious society, I am concerned about any potential damage done to property stored in the garage. Also, there is the safety aspect e.g. electrical appliances.

The garage is not waterproof and it doesn't even lock so really the tenants shouldn't be storing valuables in there or keeping plugged in electrical appliances at ground level, so on. It's basically a workshop style garage with a dirt floor.

Am I being overly paranoid?

Short of getting rid of the tank (which would be an awful waste considering we're supposed to be conserving water), I can't see a solution.

Because of the layout of the yard, the overflow pipe cannot be extended to another spot without creating a potential safety hazard.

I'm not prepared to hire a gardener just to spray some water every couple of months and doing it myself is not an option.

Thoughts?

 

[Jake D]

Can you dig in a small soakwell and connect the overflow to that?

 

[Fifth]

Should've mentioned, clay soil...

I'll try a trial pit to get a feel for the percolation but I'm not overly hopeful.

Alternatively, I believe ag drain works better with clay than soakwells, though this will require some landscape tweaking...

Cheers for the advice, Jake.

 

[Rolf Latham]

dumb q

why isnt the tank overflow connected to stormwater ?

t
arolf

 

[Fifth]

Not a dumb question. A good question. But I did not install the tank so I cannot answer. It's an amateurish job. No storm water drain nearby.

 

[Doovalacky]

Is there somewhere you can take the overflow to in ag drain then bring it back up to the surface so it waters lawn or garden? 90deg bend then a downpipe grill at end of pipe.

The other option I have done at my place on a tank is put a 12mm fitting 3/4 the way up. This allows the tank to catch a moderate amount of rain before overflowing then slowly drain into a fishpond in my case.

 

[Fifth]

Is there somewhere you can take the overflow to in ag drain then bring it back up to the surface so it waters lawn or garden? 90deg bend then a downpipe grill at end of pipe.

This is what I'm leaning towards at the moment.

The other option I have done at my place on a tank is put a 12mm fitting 3/4 the way up. This allows the tank to catch a moderate amount of rain before overflowing then slowly drain into a fishpond in my case.

Just to clarify, the 12mm fitting is a water outlet so tank starts draining at the 3/4 mark?

 

[mattysavager]

Just add a special condition to any lease that reads:

"Water in rainwater tank must be used or emptied regularly to avoid overflowing during heavy rain. The garage can be flooded if this happens. Tenant agrees that the owner will not be held responsible for any damage to the tenant's belongings due to the above issue, and it is the tenant's responsibility to monitor the level of water in the tank"

They'll sign and agree, and then it's not your problem any more.

Matt

 

[Fifth]

matty, that was one my first thoughts but I abandoned it (tenants won't like it, a bit dodgy to leave a floodable tank, blah blah) but I think you're right and I'm just over-complicating a simple issue.

 

[Nemo30]

Is there somewhere you can take the overflow to in ag drain then bring it back up to the surface so it waters lawn or garden? 90deg bend then a downpipe grill at end of pipe.

The other option I have done at my place on a tank is put a 12mm fitting 3/4 the way up. This allows the tank to catch a moderate amount of rain before overflowing then slowly drain into a fishpond in my case.

How do you get it to come back up to the surface? I'm in the middle of a project along the lines of what you mentioned, however I've been digging my trenches all downhill with a large hole for a soakwell at the end - I've also got heavy clay soil, but couldnt work out what else to do other than digging up my paving which I didn't want to do.

If I could get it to come back up to the surface that would be great, however I thought If i raised the pipe it would run back to the entry point.

Edit - I guess it would work on a sloping block. Hadn't thought of that. My block is flat

 

[Doovalacky]

Tank overflow is about 2m above ground, so you can actually make the water run uphill if needed!

But it will work on a normal downpipe as well. I just bring the pipe right up to the downpipe with the square adapter. As long as the outlet is lower it will flow out there first. Which is good in a heavy rain when the soakwell/ag pipe can't keep up its less likely to come out at the house.

Fifth,
Yes I meant to say a bulkhead fitting. It won't stop it flooding in a heavy/sustained rain but its one way to ensure a bit of breathing room.

 

[Hoffy]

Just add a special condition to any lease that reads:

"Water in rainwater tank must be used or emptied regularly to avoid overflowing during heavy rain. The garage can be flooded if this happens. Tenant agrees that the owner will not be held responsible for any damage to the tenant's belongings due to the above issue, and it is the tenant's responsibility to monitor the level of water in the tank"

They'll sign and agree, and then it's not your problem any more.

Matt

Don't know where the house is, but surely if it is in suburbia, the set up is illegal. Such a condition as above wouldn't be worth the paper it was written on would it?

Could you disclaim away illegal wiring, plumbing as well?

 

[mattysavager]

I don't know if it's illegal or not, it sounds like it might be against building regs, but a tenancy tribunal really wouldn't consider that in practice.

It's really no different to the tenant filling up the bath and letting it flood the bathroom.

I expect a tenant to maintain the property in any way that doesn't require special skills or equipment. If a tenant wants to rent a house, they look after the lawns, pool (and rainwater tank).

If it was my property, I would have had it overflow drained in the first instance, however from the OP's post, it sounded like that was unfeasible.

It sounds like his main concern was being sued by a tenant. I don't think he's got much to worry about in that department if he uses a simple clause.

 

[Fifth]

Bah. I had no part in installing it, it was there when I bought the place, but I'm reluctant to get rid of it (it really isn't 'up there' with faulty wiring), but if it comes to it I might get rid of it... I'm still leaning towards ag drain, hopefully I'll be able to bring it back up to the surface.

Thanks for all the suggestions, peeps.