Rainwater harvesting from asbestos garage roof - is it safe?

it wont cause any harm. asbestos is inert. if you damage the roof then dont breathe in the dust. thats the dangerous bit.

My guess would be it would be fine as long as the roof is in good condition, however this is a complete guess and all asbestos even the sheets should be treated very carefully therefore I would not use the water, I would replace roof with plastic , imagine giving the veg to friends and family with that in the back of your mind , even if it's ok ,you would still worry so dont do it.If the soil did filter the specks of asbestos you would then end up with contaminated soil , if the soil dried out the dust could rise into the air again causing further contamination.

Hmm, I think you are being a little overcautious on this one, Maccrimmon. Asbestos is not toxic, as such, the problem to human health from asbestos is inhaled fibres in the lungs causing asbestosis. Fibres that get washed off the roof into the rainwater butt will be damped down and can no more become airborn than the ones off the roof. Plants cannot absorb fibres from the soil so there should be no issue in the food chain. As an (ex) proffesional environmental officer I would advise anyone with an asbestos roof to leave it alone as long as it is sound. More harm to the environment is likely to be done by breaking it up to remove it than by leaving well alone. On top of which it now costs a fortune to dispose of the old asbestos and you are not allowed to re-use it.

Bulba as I say if specks are carried from the roof and go into the butt the water will then be used to water the plants drying out on the soil they could indeed become airborn ,fibres are the problem ,the roof being 1950's will have hairline cracks reemed out bolt holes etc etc this is undoubtedly a hazard .

As B has tried to explain the problem is with the fibres... NOT the odd air-born one but the fibres that are released when an asbestos panel is removed from where it is. Then those who are working on the panel will be breathing the fibres directly into their lungs - hence the health and safety problems. Watering the soil with water than has run off from an asbestos roof is not the same thing at all.

resuspension of fibres on the ground not the water butt can occur , I am well aware of the issue with fibres as I said in my previous comment "fibres are the problem".

There are different types of asbestos, some more harmful than others. a few years ago I had to have my kitchen ceiling removed by men in white suits because the insurance company found 1 part per million of asbestos fibre in the artex. Could I suggest either contacting your local Health and safety executive office or your local council for advice?

I agree totally with Bulbaholic and Moon, the odd fibre being carried in water onto the soil will not cause any problems at all. When you dispense with asbestos, it is recommended that you spray the panels with water to damp the fibres down whilst breaking it up, the fibres are washed away and are not in any great amounts that will do any harm when drying out unless you are sniffing the ground around where they have been. If you want to get rid of the asbestos, phone your local authority, they should have a place it can be taken and they will issue you with a permit to do this as it can only be done on certain days