[effluvium]

Wow. You make a great point. You got me thinking about those rainwater capture systems for downspouts now. Rainwater hits asphalt shingles and picks up a bunch of hydrocarbons, and then someone uses the contaminated water to grow their tomatoes.

[schiffern]

The standard recommendation is to avoid shingle roofs for rainwater collection, and use a non-toxic metal or tile roof instead.

Ignore the advice saying plant cells or fruiting bodies can "keep out" pollutants; this isn't true across all classes of pollutants, so best to err on the safe side.

[pvaldes]

If you grow vegetables in an urban environment the rain will bring a lot of undesired things in any case. Is unavoidable. Regulations (and the complicated plant metabolism) can fix that

Apart of that, is not required to wash the tomatoes directly with the grey water. Just soak the roots and the organism will take care directly of the recycling and classification of water and other stuff. Everything nasty stored in roots, stems or leaves is harmless and equivalent as cleaning it from the environment for free. Only fruits will count. Cells are good at keeping out what they don't like; and store the things that they like.

[RetroTechie]

> If you grow vegetables in an urban environment the rain will bring a lot of undesired things in any case.

Apart from areas with heavy air pollution, rainwater as it falls from the sky is generally clean enough that it's safe to drink. Almost anywhere on the planet.

But! As soon as it hits a surface, it's easily contaminated with anything & everything: bird droppings, lead (used as an additive to zinc) from galvanized corrugated steel, etc etc.

Basically: in most places, rainwater is as clean as the collection surface / piping / storage equipment used.

[bamboozled]

This is shit is going into every water table we have though, all the run off from the roads, tarmacs, roofs, fake grasses, it’s all contaminating the world.