grey water and composting toilets

[UndercoverElephant]

OK...another question about the smallholding we are in the process of buying. Currently all of the waste water goes into a septic tank that has to be emptied once a year. This seems to be horribly inefficient - we would be paying for metered water for baths and showers which is then needlessly contaminated with sewage, which we then have to pay somebody to take away. If there's hot weather and we have lots of vegetables that need watering then we will end up having to pay for more metered water to do that. Presumably we can change this system so that grey water from the bathroom (and possibly the kitchen?) goes into a different tank which can then be used to water plants. Right?

We will also be installing a composting toilet, both because humanure is a useful soil improver and because we'll need one if we are going to go down the glamping route. Although we wouldn't be using it all the time, so the septic tank would still be in use - it just wouldn't need emptying anything like so often. Is there a time limit on that? Do you eventually have to empty it even if it isn't full, just because it hasn't been emptied for a certain period of time?

[Catweazle]

Common practice here is to install a septic tank to current regs, then drill a load of holes half way up it so it acts like a soakaway. There are houses that only have to pump out their tank every 15 years, and it costs peanuts if you get a local farmer to do it with their slurry vac.

Because of the age of our house we actually have a legitimate soakaway, but previous owners had to get a certificate from the council approving it. It's dealt easily with everything we've flushed into it plus countless gallons of rainwater from the house roof. It's recommended that you don't extract drinking water within 100m of a soakaway.

Water costs £1.40 per 1000L, not a lot, you can get used 1000L IBC water containers for £35-£50. One or two on each corner of your barn will give you a good reserve.

[UndercoverElephant]

Common practice here is to install a septic tank to current regs, then drill a load of holes half way up it so it acts like a soakaway. There are houses that only have to pump out their tank every 15 years, and it costs peanuts if you get a local farmer to do it with their slurry vac.

Because of the age of our house we actually have a legitimate soakaway, but previous owners had to get a certificate from the council approving it. It's dealt easily with everything we've flushed into it plus countless gallons of rainwater from the house roof. It's recommended that you don't extract drinking water within 100m of a soakaway.

That is a not a great idea from our point of view, because we would be polluting our own spring, which is less than 10m from the tank.

[kenneal - lagger]

There seems to be a common error going on here. There are two older types of rural sewage systems which are used in different circumstances.

Where the ground drains well a septic tank is usually installed. This is a tank which separates solids out from the sewage and retains them and then sends the liquid out through a distribution system to drain into the soil. If you have well water this drainage system should be installed well below any water catchment system so that there is no contamination of the fresh water system. If you use well or spring water most local authorities will want to test the water for faecal contamination on a "regular" basis, especially if you have a camping or tourist business of any sort. The outflow from the septic tank can be arranged to flow under your vegetable garden to great effect especially in dry years and soils which suit a septic system can usually do with the help in dry years. The septic tank is usually recommended to be emptied once or twice a year depending on use; many have never been emptied and there are commercially available enzymes which can assist in this by breaking down the solids in the system.

In areas where there isn't a soil with suitable porosity for a septic system to drain properly a cess pit is generally used. This is sunken tank usually between a 1000 galls or 6000 galls for more modern units serving larger houses which holds all the sewage coming from the house. These are the ones which people knock holes in. If your soil has been assessed properly this won't make much of a difference because the soil will be too glutinous to let any water through. Cess its are generally avoided like the plague because of the cost of emptying them.

A composting loo system with a grey water disposal system is a newer way forward, I say "newer" because we put one in 40 years ago and they were sort of new then, which can be incorporated into vegetable gardening very well. It would be really good for your area , UE, with thin soil over a rocky sub soil by building raised beds to get the soil depth and then running your drainage pipes under the beds. Our drainage system runs under raised beds in our polytunnels to irrigate them and we have a branching valved system so that we can control where the grey water goes. If you have to pump the water pump it to the top of the system and let it drain down into the drainage field from there. It is best to keep any such system away from your water catchment area as although the bacterial load will be low there can still be some bacterial load and taste issues.

Hope that helps.

[emordnilap]

We're lucky to have a really good soakaway for all our grey water. I put guttering along both sides of the polytunnel, bringing us up to about 16,000 litres of rainwater capture, so never felt the need to recycle that grey water.

Our compost loo is where the toilet was (I removed it and its plumbing) and I wouldn't go back to an old-fashioned flush loo. I even hate going to the loo in someone else's house, what a waste! You should save every scrap of your 'output' if you can, along with absolutely everything that's compostable: paper can labels, shredded paper, string, fallen leaves tissues, anything that'll biodegrade (tear open used tea bags and put the leaves in, the bags usually have some plastic in them), just be obsessive.

[UndercoverElephant]

I find normal teabags completely compost. You can tell the ones that have plastic in - they feel different.

[Lurkalot2]

(tear open used tea bags and put the leaves in, the bags usually have some plastic in them), just be obsessive.

I'll have to show your post to my daughter. I tear open teabags for the compost heaps and she said to me the other day " no one else does that" . Good to know I'm not the only one although like UE says a lot of teabags don't have plastic nowadays.

[BritDownUnder]

This seems to be horribly inefficient - we would be paying for metered water for baths and showers which is then needlessly contaminated with sewage, which we then have to pay somebody to take away.

Given at least one of your family's penchant for hot baths you could also investigate the possibility of heat recovery from the hot bath water.

It's great to have your own place, particularly detached and not having too nosey many neighbours close by so you can do all kinds of experiments.

[emordnilap]

I find normal teabags completely compost. You can tell the ones that have plastic in - they feel different.

Right. That's good. Not a big tea drinker so I never notice such things.

[kenneal - lagger]

We're lucky to have a really good soakaway for all our grey water. .......................... what a waste! You should save every scrap of your 'output' if you can, .................

What about all the nutrients in the grey water? Most washing up liquids and many hand wash liquid soaps have valuable phosphates in them and well as all that skin and hair and food waste.

[emordnilap]

We're lucky to have a really good soakaway for all our grey water. .......................... what a waste! You should save every scrap of your 'output' if you can, .................

What about all the nutrients in the grey water? Most washing up liquids and many hand wash liquid soaps have valuable phosphates in them and well as all that skin and hair and food waste.

As the house is at the lowest point of the site, it's not that easy to re-use the grey water.

[kenneal - lagger]

Our greywater goes into a sump with an electric submersible pump in it controlled by a float switch. From there it is pumped directly into pipes under the beds in the polytunnel.

[emordnilap]

Our greywater goes into a sump with an electric submersible pump in it controlled by a float switch. From there it is pumped directly into pipes under the beds in the polytunnel.

That sounds great. Something to put on the list. It's about 60 metres from the greywater outlet to the entrance to the polytunnel, uphill all the way, aargh.

[kenneal - lagger]

Just make sure that the pump that you buy can handle the head it will have to work against plus a bit, 10%?, for pipe friction.