How can I protect my garage cabinets from floodwater?

Hello @Bluetooth

Welcome to the Bunnings Workshop community. Thank you so much for joining us and sharing your question about how to protect your cabinets from floodwater.

Your idea of creating a frame with castors is the best one. You could create a sloped cement dam to divert the water coming into the garage. Unless the water is coming in from someplace else? I suggest using Treated Pine Outdoor Timber Framing 70 x 35mm in conjunction with Zenith 10 - 8 x 75mm Galvanised Countersunk Rib Head Timber Screws - 50 Pack.

I recommend using Project Panel 1200 x 1198 x 12mm Premium Plywood. This will protect the bottom of your cabinets from accidental splashes from the bottom. I propose using Syneco 100mm Blue Rubber Castor Set - 4 Pack. These castors will add an extra 100mm to the height of your mobile frame giving you extra flood safety. For the final touch, I suggest painting it with Taubmans Low Sheen White Sunproof Exterior Paint - 1L White.

Please keep us updated with your progress, we look forward to seeing your rolling frame built and in use.

Let me tag our experienced members @TedBear and @JoeAzza for their recommendations.

If you need further assistance, please let us know.

Eric

Jason

Hi @Bluetooth,

Let me also extend a very warm welcome to the Bunnings Workshop community.

Just wondering if we might be able to assist with the flooding problem? If you shared some more details and photos of how the water gets in, I'm sure the community would be happy to help.

Jason

JoeAzza

Hi @Bluetooth ,

@EricL great suggestion, this would keep your cupboards off the concrete, also as @Jason suggested you need to find where the water is coming in from and seal the ingress area if possible.

Another quick fix is to install plastic adjustable legs to the shelving/cupboards, install them behind the kick rails, front and back of each unit, then adjust the height as required.

Hi @Jason,

Thanks for the response. Ah, the flooding issue. This has been an issue since moving into this home. The driveway slopes down from the street to my garage - there is a pit with a sump pump which pumps water up and onto the street. Additionally, about half of the house's roof drains into rainwater tanks which overflow to the same pit. When it rains a lot, there is a large volume of water that comes into that pit. The sump pump works most of the time, but occasionally it just doesn't turn on - possibly because the water is flowing onto the float at too rapid a pace. Also, sometimes the pump doesn't work, just because the float doesn't trigger. In those cases if i come out and jiggle the float, the pump will usually start up. However, I'm usually not in the garage watching the pit, and when it does overflow, it will fill 3/4 of the garage with an inch or two of water. I have replaced the existing sump pump with a Ryobi from Bunnings, but I still have the issue. I have considered getting a more substantial more expensive pump as a solution, but have not followed through.

@EricL's suggestion of a cement barrier to divert the water is very interesting. I believe that a barrier with height of about 80-120mm across the front of the garage would be high enough to divert the water to the side past the heat pump (in the photo), and under the fence away from my house. You can see there is around 20 cm of space between the drainage trench, and the spot where my garage door meets the floor. Of course, the garage door could also be adjusted to land on a barrier as well. Maybe I could build a 'speed hump' out of cement in that section that is 200mmw x 100mmh x 2000mml. Of course I would still use the sump pump 99% of the time, but on those 2 days a year when the pump fails, I will not have to dry out all the items on my garage floor.

Maybe I should start a new topic for this question, since I already marked the topic as 'solved'?

Thanks so much for your help. Its great to bounce ideas off people with expertise and interest!

Jason

Thanks for the photos and detail. No need to create a new topic @Bluetooth.

Let me tag @MitchellMc for his thoughts.

Jason

Hi @Bluetooth,

I have a similar pump, and the float switch can be a bit finicky. It likes to turn completely vertical before it activates. Make sure you have the floats lead shortened to the correct length for the pit. You'd want it nice and short, but not so short that the float valve can't float up into a vertical position.

How often are your rainwater tanks full? Could you consider irrigating your plants more often to keep the tanks 1/2-3/4 full most of the time? That way, if you have a torrential downpour, the bulk of the water should hopefully end up in the tanks before the pit.

Instead of building the cement barrier, you could potentially cut a channel in the concrete as an emergency overflow. Once the water reaches the brim of the pit, it could follow the channel past the heat pump and under the fence. If you did build a cement barrier, will your vehicle easily get over it? I've found some concrete edging that looks like it would be pretty good. I suspect it won't hold up to a car driving over it constantly, though.

If your gutters are higher than the street level, have you considered moving to a charged system? I suspect the road is relatively high, as a pump system usually would not be the first choice, mainly due to them failing or not operating during a power outage.

I'll be looking forward to seeing how you solve this issue. Please let me know if you have any questions.

Mitchell

Hi @Bluetooth , this is a challenging issue. I look forward to seeing how it gets resolved.

The drain at the entrance to the garage is very much an "ambulance at the bottom of the cliff" approach.

I had a similar one across the back area of my house, inviting all the water from the sloping back yard to the arrive at the back door. I was able to change things by replacing much of the hard surfaces with absorbent ones and also collect and divert water before it gets there, so those drains are now gone. But with a driveway, you have less options. My suggestion would be to put a channel drain across the driveway further up and divert the water into a soakwell, assuming that your soil type will soak up some water. Is there a garden area where any excess could be diverted to? (Anything to keep water away from the garage door.) That way the current system will have less water to deal with and will hopefully cope in a storm.

Hello @Bluetooth

Would it be possible for you to post a few photos of how the water flows towards your pump and how your tank overflows are arranged? Once we see the path of the water we should be able to give you a more comprehensive recommendation of how to divert the flood.

Eric

@MitchellMcfunny you should ask about a charged system. About 2 months ago I had to get the concrete pad for the rainwater tanks replaced as the original one had shifted. A plumber quoted to replace the whole system with a charged system, but it was for $9k and I couldn't afford that. The driveway is upward sloped but the rise is not that high. The gutters on the roof are above the street.

Instead I had the slab replaced but now I'm wondering if I made the wrong decision. I wonder if I could DIY it so that some of the water is diverted to the street. Sounds like a big project.

Your concrete edging ideas sounds interesting as I don't actually park the car in the Garage and they are not permanent which MAY be a plus.

Hi @Bluetooth

You can definitely D.I.Y. a charged system. However, if you do it above ground it won't look very nice. I suggest reviewing your current setup and seeing if there are any bottlenecks or areas that trap water. An easy solution is to use a bigger pump pit so that the mercury float or pump switch is not agitated when water comes down to the pit. You can install a gravel pit to slow the water down so that the pump has enough time to get rid of the water that's currently in the pit.

Please keep us updated with your progress, we look forward to seeing your flooding problem sorted.

If you need further assistance, please let us know.

Eric

@EricLThanks for your suggestion. I think the best solution might be a wet or dry pvc system that goes from the overflow of my rainwater tank out to the street. There is a fence and a hedge for most of that distance, so it would be mostly hidden from view. The wet system would be more hidden as it could be on the gound, but the dry would be more maintenance free going forward.

Hi @EricL and @Bluetooth I wonder if I am the only person who does not know what a charged system is...? Would you mind explaining it for those of us unfamiliar with water systems please?

TedBear

@TedBearThat's a great question, and before my plumber suggested it, I had never heard of a charged system either. Especially coming from a country where temperatures drop below freezing, it would be unheard of! Correct me if I'm wrong, experts, but a charged (or wet) stormwater system is one where there is always water in the system. Like a trap in plumbing, water moves through the system, but its natural state is full of water. The use case is when you need to move water up hill. Perfect situation is when the roof is above street level, but floor level of the house is not. So the top of the charged system might be at the top of the eaves, and the pipe runs down and under ground, then up hill to street level, and drains there. As long as the end at the street is lower than where the water enters the system, then during a downpour, the water should flow out at the street. Downsides is that the system typically traps debris, so can get gummed up. Upside is that all the pipes are hidden underground (usually).

Hi @TedBear,

@Bluetooth is spot on there, but don't worry, I too had only become aware of them recently.

The rendering I've put together would be just about the limits of a charged system where the street is just below the gutter. In an ideal world, your stormwater would run downhill into the main collection line, but sometimes, as is the case with steep blocks, that isn't possible. Apparently, most councils prefer a charged system over a pumped system and will give a certain amount of leniency to alter the council strip, allowing the installation if the only other option is a pumped system. The issue with pumped systems is that in the event of a massive storm, power goes out reasonably frequently. It might only be once a year or every two years, but in those events, pumped systems fail and flood properties.

Mitchell

Thank you @Bluetooth and @MitchellMc for the excellent explanation and for the diagram. That makes sense as a potential solution for the overflow.

pstq

I get about a centimetre of water in the first metre of so of my garage if it rains hard. I just put everything down that end up on bricks. I can't put a lip across the front to stop it flowing in because it's a tilt door, and it would stop it opening.

I have a similar problem with too much water coming off the garage roof that can't be fed to the house drain. I have them feeding into a tank. I keep the tank half full by feeding water from the tank tap to the trees in the paddock over the back fence via a hose. Halfway along the hose, it hangs on a hook on the fence, and has a hole in it to stop it siphoning. When the water level falls to the height of the hook, it slops flowing. So the tank is half full and can catch a big downpour and let it out slowly.

Could you put the lip behind the tilt door where it doesn't inhibit its ability to open @pstq? You'd then have to enclose the sides and box in the bottom of the door.

That sounds like a fairly brilliant idea with the hose elevated midway and I would have never thought of placing a hole in the top to stop siphoning.

Thanks for sharing.

Mitchell

pstq

The door problem is more complicated than that. The slab has dropped a little, so if I put a barrier behind the door, it would form a narrow pond with the door sitting in it. I probably need to cut the bottom off the door, and fill that depression. One day.

This is the hose arrangement. It doesn't just have a hole, it has a short vertical section off it. That's so a full tank won't have water spurting out the hole onto the fence.

Hey @MitchellMc That drawing looks pretty good! In my case, the source would actually be the overflow from my rainwater tank (red circle in photo #1). You can see that it currently drains into the pit at the front of the garage (green square in photo #1), so when the tanks are full, and its raining hard, there is a huge amount of water that goes into the pit, and sometimes floods the garage.The sump pump moves the water along the fence to the top of the driveway, and into a pit which drains out into the street. You can just see a little of the pvc sump pump pipe next to the bins in the photo #2.

Now I think the best solution is to run a new 90mm pvc stormwater pipe from the top of the rainwater tank down (blue line in the photo) and along the fenceline at ground level to the front of the property to drain into the existing pit. That way it would flow to the street, without needing to be pumped up the hill. The system would need to be charged, I reckon. I don't plan to bury it, as it will not be visible since its behind hedges for 90% of the distance.

Any thoughts on this idea? After watching a few Youtube videos, I think I should use T-joins instead of elbows near the bottom of the charged system, for access in case i need to clean out debris.

Rainwater tank overflowDrain would run along fence

Hi @Bluetooth

I suggest putting in a Holman 90mm 90° Female And Female PVC Stormwater Junction with a Holman 90mm Threaded PVC Storm Cap. The important part of this assembly is that the O-ring sits firmly on the inside of the cap. This is to prevent air from entering the charged area. A good position for them would be one on each end after the turn and one in the middle of the run.

However, before you proceed with your proposed project, I encourage you to have a look at the water tank overflow discharge regulations in your local area. It sounds like a fantastic project, any updates you can provide would be much appreciated.

If you need further assistance, please let us know.

Eric

@Bluetooth,

What's the elevation change between the street and the front of the property? From your image, there appears to be none or such a slight difference that correct installation of stormwater pipes with an adequate fall could easily transfer water to the front of the property without the need for pumps or a charged system. Charged systems are usually only considered if an elevation difference is more than what can be countered with a fall in the pipe.

I'd imagine it would be just a case of measuring the distance from the street to the rainwater tank. Say it is 20m, you'll need to bring the pipe down from the tank to 20cm's above the ground and add a Holman 90mm 45° F-F PVC Stormwater Elbow and Holman 90mm 22.5° M-F PVC Stormwater Elbow to get a bend of 67.5 degrees (or thereabouts). Then you'd run the pipe to the street at a gradual fall of 1:100. So, for each of the 20 metres, you'll drop 1cm in height.

Please be advised that in most locations around Australia, you'll need to employ the services of a qualified stormwater/drainage professional to change this pipework. I'd encourage you to seek out their services, especially for the charged system, as that is something you'd really want to get right.

Suppose there is no particular difference in elevation between the street connection and the house. In that case, I wonder whether the stormwater pit is actually the cause of not having a standard setup. Is the pit dropping the water so low that a standard fall can not then be achieved? Perhaps without the pit, you could have the whole house's pipes run directly to the street.

Mitchell

Option 1 - DryOption 2 -Wet

The drawings above are the two best options in my opinion. They're not exactly to scale, but give a decent idea of whats going on. 90mm pvc pipe.

A friend prefers to put a hole half way up the irrigation tank, and use 50mm black slotted draincoil. He argues that the hydraulic head from half of the tank will be enough to push the water out and up to the pit at the top of the driveway. I'm not sure if I could cut the tank and install the fixture to take the draincoil myself, and it risks the irrrigation tank to puncture it, if something goes wrong. The 50mm coil has the advantage of being cheaper than pvc, since i have about a 20m run.

There are some interesting points to consider in @Bluetooth 's suggestions. I am not sure that I'd be putting holes in an existing tank, nor do I see water "pushing" water uphill. It just falls until the levels at each end of a pipe are even (if levels allow that to happen, else it drains away). I don't think there's a need to be making extra holes in the tank. The existing outlet at the bottom can be cut into and a T piece inserted. That way a Standpipe can be put up the outside, which will contain water at the same level as the inside of the tank. Then you place a T connection in that pipe, at the height of the tank that you want to draw water down to. (If using this method, make sure that the top of the standpipe is open to air or the water could be siphoned from the tank instead.)

@TedBear , @MitchellMc @EricL @Jason

I managed to finish the project over the holidays with the help of my FIL. I'm happy with the results, and the water now drains to the street with gravity. The pit by the driveway is still necessary, as I found that some water still ends up there, but much less now.

new 90mm gravity feed next to the old 40mm pumped out water

new irrigation tank overflow

gradual fall along fence

mostly hidden by bushes