Growing crops near a septic tank questions

[UndercoverElephant]

Does anybody have a reliable source of information on this? Because googling for it produces a lot of results which I'm not minded to trust -- it looks like quite a lot of well-meaning people repeating warnings which don't fully make sense. For example, they mix up crops grown by applying untreated wastewater and those grown in drainage fields where the water is "partially treated" and the distribution is entirely subterranean. They also frequently fail to distinguish between different sorts of crops (there may well be a big difference between growing root crops and growing raspberries, for example), and don't explain the reasoning behind their warnings. Some articles actually talk about "contamination with P and N".

What I am looking for is a website or a book which sticks to the facts instead of "erring on the side of caution" to the extent where you can no longer trust the information you are being given. I need to decide where to grow various crops, and most obvious choice is an area about the size of a tennis court between a septic tank and seasonal stream. It is close to the house, flat, sunny, sheltered from the prevailing wind, below the roof level of the main buildings (so easy to supply roof water to). The presence of the septic tank is both a worry and a potential benefit, for obvious reasons. In terms of nutrients and soil quality, as well as groundwater supply, I would not be surprised if it is the best place in the whole 5 acres of land we are buying. It seems a waste not to use that for something, especially as doing so will presumably actually improve the quality of the water that leaves this site and enters the stream (there is a spring between the drainage field and the stream, which I presume predates the septic tank because it is marked on old maps).

[Catweazle]

Perhaps you could use this fertile but maybe not entirely safe area to grow crops not directly for consumption, for example you could plant small batches of various plants for seed production - beans, peas, squashes etc. for planting out into larger areas.

[clv101]

Personally, my uneducated guess, would be it's okay to grow in. The only thing I've slight concerns about would be root veg, especially those you might eat raw like carrots.

I'd be happy with peas, beans, brassica, etc

If you are really concerned, how about fruit bushes, grape vines, fruit trees?

[UndercoverElephant]

I am not actually concerned at all. I think most of what I'm finding written about it is probably nonsense. I just thought I'd get a second opinion!

[emordnilap]

The answer is always, use a dry toilet, forget the septic tank. It's the easiest way to use human shit and piss. Little equipment, little smell, little work, almost cost-free and certainly worry-free.

[UndercoverElephant]

The answer is always, use a dry toilet, forget the septic tank.

I can't do that, mainly because the tank is already there and I cannot tell everybody, including visitors, to use the dry toilet. The septic tank will get considerably less use when we move in, but it has been there for many years and will inevitably stay there.

[kenneal - lagger]

Take the wet loo out and replace it with a dry loo then there is no choice.

We set the drainage field for the septic tank in our old house under our vegetable garden. The pipes for the field were about 1200mm deep but we used to get carrots about 225 long and parsnips 450 long with probably another 150 left in the very sandy soil. We never had any illness problems although we did eat the carrots cooked.

Depending on the depth of the drains I wouldn't have thought that growing above ground crops would cause any problems and root crops should be OK if the drains are deep enough. As long as you cook them there shouldn't be a problem no matter what the depth. If you need a lot of carrots for grating and eating raw grow them elsewhere.

[UndercoverElephant]

Take the wet loo out and replace it with a dry loo then there is no choice.

I am not going convince other people to agree to that. It would also have a negative effect on the value of the property.

We set the drainage field for the septic tank in our old house under our vegetable garden. The pipes for the field were about 1200mm deep but we used to get carrots about 225 long and parsnips 450 long with probably another 150 left in the very sandy soil. We never had any illness problems although we did eat the carrots cooked.

Depending on the depth of the drains I wouldn't have thought that growing above ground crops would cause any problems and root crops should be OK if the drains are deep enough. As long as you cook them there shouldn't be a problem no matter what the depth. If you need a lot of carrots for grating and eating raw grow them elsewhere.

Yeah, that's what I was thinking too. Although I don't know how deep the drains are.

[Catweazle]

I've been searching for information on growing near a septic tank, and as UE says it's difficult to find an authoritative answer. It seems unlikely that micro-organisms can be absorbed into a plant, but my worry would be about chemicals, especially if previous owners had been using hormone replacement medications or oral contraceptives.

[UndercoverElephant]

especially if previous owners had been using hormone replacement medications

I hadn't even thought of that one. I wonder how long it would take for something like that to flush through the soil.

[Potemkin Villager]

Can anybody explain why there is so much extreme paranoia about human shit whilst folk are quite
happy piling, well rotted of course, animal shit on their pristine organic veg patches?

[kenneal - lagger]

Take the wet loo out and replace it with a dry loo then there is no choice.

I am not going convince other people to agree to that. It would also have a negative effect on the value of the property.
...........

Are you really looking to sell the property having only just bought it? If it had that much affect on the property price you could always reinstall a flushing loo before selling.

Sounds like a trial hole is called for to see what your problem might be. It would be worth seeing what the condition of the system is anyway to check that it will work as grey water drainage if the flush toilet is removed.

[UndercoverElephant]

Take the wet loo out and replace it with a dry loo then there is no choice.

I am not going convince other people to agree to that. It would also have a negative effect on the value of the property.
...........

Are you really looking to sell the property having only just bought it? If it had that much affect on the property price you could always reinstall a flushing loo before selling.

We have no intention of selling. To be honest I am just trying to close down this line of debate because I know I will not be able to convince my other half to get rid of the flushing toilets, because it won't be popular with visitors. No point in talking about it because it is not going to happen.

[kenneal - lagger]

I am not going convince other people to agree to that. It would also have a negative effect on the value of the property.
...........

Are you really looking to sell the property having only just bought it? If it had that much affect on the property price you could always reinstall a flushing loo before selling.

We have no intention of selling. To be honest I am just trying to close down this line of debate because I know I will not be able to convince my other half to get rid of the flushing toilets, because it won't be popular with visitors. No point in talking about it because it is not going to happen.

Sorry to keep it going but on but our guests don't seem to mind our composting loo. They just accept it as one of our "eccentricities"!

[clv101]

....because it won't be popular with visitors.

We've had exclusively dry composting toilets for ~5 years. Have lots of visitors, public tours, events, hosted training courses etc. Never, once has anyone expressed any concern/problem with the toilet. Many folk have made positive comments. Maybe, everyone hates it but are too polite to say anything? I don't concern myself with it! We're very pleased to have dodged the issues of dealing with black water on our site which wouldn't have been trivial given the topology.