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Grey water tank


Geoff and Pam Ward

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On a recent trip around Tasmania, we found a few camp sites which had rules that prevented the disposal of grey water on the ground (no sullage drain was available). In one case, we were not permitted to enter the site unless we had a sealed grey water tank installed (which we did not have). I also found it to be mildly embarrassing when we park in a town somewhere for lunch and when we have finished the washing up and hand washing, there are a couple of pools of grey water under the van or flowing across the street.

We therefore set about to install an extra tank for storage of grey water. I could not find an off-the-shelf tank to suit my needs, mainly because they did not have inlets and outlets where I wanted them and of the size I required. I therefore had a tank custom made by Abber tanks http://www.abbertanks.com.au/. Their service was very good and the tank appears to be well made.

I have separate 1 inch inlets for each of the kitchen sink, washing machine and bathroom, and 2 outlets: 1 inch on the RHS (with a tailpiece for connecting the usual Kedron hose to a park sullage drain) and 1.25 inch on the LHS which might help with quicker dumping of the waste water at the side of the road. These outlets are fitted with plastic ball valves. There is also a 3/4 inch breather/overflow outlet on the top of the tank. No more grappling with the tee piece drain hose supplied by Kedron for connecting the bathroom and kitchen to the sullage drain!

The tank we had made will hold about 125 litres. It weighs just 10kgs and with the holding basket and plumbing the total additional weight is about 15 kgs. There is no additional water weight as it only involves a transfer of water. On our 21 ft Top Ender, I had to move the rear water tank 6 inches forward to make room for the new tank. This was not difficult and required no re-plumbing.

I made up a steel basket to hang the tank in place. The steel used was 19mm x 3mm mild steel flat and I reinforced the 3 bottom bars with a pieces of steel on edge to give it some rigidity - see photos. I also welded some 6mm x 19mm flat to the anchor points of the basket to give them extra strength. The steel basket was lined with foam rubber of the type used for expansion joints in paving - from Bunnings. The stone guard on the front of the basket was made from a split piece of 4" x 3" gal down pipe and the stone guards protecting the ball valves and outlets were made from a piece of circular downpipe from Bunnings. Mounting brackets for the ball valve stone guards were made from 19mm x 3mm flat.

If anyone would like to know more about this or wants a copy of my drawings, please contact me on gward1211@bigpond.com

Regards

Geoff

Caravan grey water tank.pdf

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Edited by Geoff and Pam Ward
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Hi Geoff

We have a grey water tank in our Kedron. You might want to consider installing a couple of HepVo valves somewhere in the inlet lines into the tank, these are a one way valve that prevent any smells, discharge etc coming back up into the plumbing system and into your caravan. You can buy them through Reece Plumbing or some other places.

Incidentally, our Kedron was the first to have grey water tank, which I designed, installed at the build stage, and is the system now used by Kedron.

Well done.

Pete

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Grey Water Tanks ???

Well this question will go on for ever.

Are they really good for the environment or do they just make some authorities and users feel good about themselves ?

Unless treated the same as your black water system grey water tanks in my opinion do more harm if operated irresponsibly.

If like we observed the other day a group of motor home owners proceeded to dump the contents of the grey tanks after camping for a couple of days as they drove out of the site and down the road past our site.

The question that needs to be asked is why did they bother to store it and let it go off so they could just dump the greasy, smelly slimy waste next time they drove down the road.

If you have ever lived with a septic system and had a grease trap this is effectively what you are installing under your vans and they need to be treated with respect as you are starting to get involved with some nasty bugs when they start breading in a lovely humid environment.

I would much rather not dispose of anything on the side of the road or at a camp site but most scraps that go down your sink are consumed by the birds and reptiles that have made these places home. I do how ever feel more comfortable dumping fresh grey water than a cocktail of sludge and slime.

Laurie

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Laurie, well said. Like everything else it comes down to how you use and manage it. Having a grey water holding tank solves nothing unless it is managed well and discharged responsibily.

Regards , Colin

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  • 2 years later...

Laurie,

Well said, Your comments should be sent to the CMCA group as they are the ones wanting this idea of self containment being compulsory.

Have also heard of motorhomes letting their grey water out along the road.

 

Bil

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We have one of these tanks under our TE and this has opened up far more freedom camping sites to us particularly in QLD.  The only problem now is disposal, after 24 hours your grey water becomes black water and therefore must be dumped at a dump point and the treatment we use is the Odour Be Gone tablets and between trips we flush it out with sodium meta bisulphate, we never keep grey water in the tank more than 24 hours if we can help it.  There are plenty of trees in the world that can use a little water if we have to drain the tank with a bucket and if kept longer, the closest dump point which can unfortunately prematurely fill them quicker.  

 

Cheers

Merv

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  • 2 months later...

I think some of the comments and concerns about grey water turning to black water after 24 hours are a bit exaggerated.  We have lasted up to 3 days without emptying the tank and when it was emptied, the water was fairly clean, non-smelling shower and sink water (no fat goes down our sink).  It needs to be dumped responsibly, which means not in town, not in a national park which prohibits dumping, a good way away from any residences and areas likely to be accessed by the public.

After our first trip with the tank, I drained the tank and stored the van.  3 months later the smell coming up through the shower waste was noticeable.  After subsequent trips, before storing the van, I put a couple of litres of pool chlorine in the tank with about 10 litres of water, take it for a drive to slosh it about, drain it, and have never had another smell.

I will consider fitting the one-way valves mentioned by Pete above.

Geoff

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  • 4 months later...

We are now the proud owners of a very good 2006 ATV 19ft 6in van.  The van is fitted with 4 water tanks.

It appears that the rear tank and the one between the axles are for drinking and sink and the front 2 for shower and washing machine. 

I would like to convert one of the water tanks to a grey water tank and I was thinking of converting the tank between the axles

as it is only a transfer of water so weight should not be a problem.

Any assistance or recommendations will be appreciated.

 

Garry

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Hi Gary

 

You might have a problem with the fall for all the piping (four from memory) depending on how the hoses are running you might be able to get away with two inlets, one for the kitchen combined with the vanity and maybe a conjoined one for the shower/washing machine depending which unit you have.  The other thing is that you would need to put in on each side a drain preferably 32mm.  You can use the existing breather on top of the water tank as an overflow to alleviate possible problems with water return. 

We had ours made by Abbertanks and they are brilliant, so it might pay to have a talk with them and this way you can decide where you actually want your inlets.breather, outlets and size and I would also look at putting a decent size drain plug in the bottom of the tank to completely drain the waste.   I also attached a 13mm hose onto the breather so I could flush out the tank after a long trip.  The longest we have kept grey water in the tank is 48 hours and have noticed a slight aroma starting to intrude into the van so now nothing is kept longer than 24 hours and this way we haven't ended up with the normal soap sludge in the bottom of the tank and hence no smells.  There are a lot of trees around that need water....

The other thing I would be looking at is having a decent guard/rack made to hold it up with a little extra on the leading edge to stop sideways slippage.

Spend a bit of time under your van and then download Geoff's design and alter it to suit your van, this I think would be a better way to go than using the existing water tank and trying to modify it.  On top of all this use SMOOTH bore hoses not the internal ribbed ones that Kedron were/are using for their waste plumbing, that is where you will get a lot of smell coming from.

 

Cheers

 

Merv

 

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Hi Merv

Thank you for the great information.  The current setup for the waste water is the en suite sink and the kitchen sink are connected together and the washing machine connects to the shower drain.  There is a large tap fitted to the shower drain hose as the previous owner mentioned that the washing machine would start to go into the shower drain as the machines pump pressure was quite strong and the outlet would have a slight restriction to the flow.  Kitchen/Vanity and washing machine connect into a T then the shower is then connected with a second T which drains all to the outside.  I was considering not having the washing machine going to the grey water tank as we will only use it when we can drain to ground or van park.  I was going to attach the waste gate (below) to the sink/vanity and shower grey water inlets to stop the odor coming back up.  I will also take your advice to use a 32mm outlet for the drain.  The existing water tank is wrapped with 1mm or 1.5mm Gal sheet screwed to the rails under the van in between the axles (independent suspension).  I am only doing this as I have 4 x 80ltr tanks and as we are only starting out we wont need all that water and will probably spend a lot of time in CP's until we get a bit more confident to start to free camp a lot more and after we retire.

 

Stay safe and thanks again for the info.

Garry

Waste Trap.jpg

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Hi Garry,

My thoughts are:

If your Kedron tanks are the same as mine they are grey plastic with Kedron impressed on them.  An initial problem will be getting the inlets into the tank near to the top. I recall that I have separate inlets for sink and washing machine and a combined inlet for basin and shower. It would not be difficult to cut holes into the sides of the tank and one in the top for a breather. I had threaded holes welded into the tank but I'm sure you could buy some sort of adapter from a plumbing or irrigation shop to which you could affix a 1" hose.  You might be able to have threaded outlets welded into the existing tank.  If not, you might be better off having a custom tank made.  Mine holds about 125 ltrs.  I have an outlet low on each side of the tank. This is handy as I can generally use a single 3 m piece of hose on either side to just let the water flow through the tank into the sullage drain in a CP.  If I'm on the side of a road I can generally dump it without using a hose. 

Regarding the possibility of sideways slippage mentioned by Merv, my tank is clamped pretty tight to the floor rails and has never moved. I was interested to keep the basket a light as possible for overall weight reasons.

Kind regards

Geoff

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Hi Geoff

Thank you very much for the reply.  All 4 of my tanks are black with ridges on the bottom.  I will over the next few weeks take the tank I want to convert out of the van and I will then have a better idea if it is feasible or not especially with the vent as I might not have enough clearance above the tank when it is in its enclosure.  All the tanks have the ends facing the sides of the van and does not give a lot of room to drill/affix/glue etc.   I will keep you all posted on how I go.

Thank you again

 

Garry

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