On Wed, 12 May 2021 08:48:44 +0000 (UTC), RJH
wrote:

snip

The estimates I generated from a variety of sources gave cow's milk 600 - 1000
litres of water per litre of milk. There is a bundle of variables that inform
where on the scale it is. I chose 628l in anticipation :-) (ref. Poore and
Nemecek)

Oat milk about a tenth of cow's milk. But that's partly due to irrigation.

Assuming any area is only irrigated by rain (and we know it isn't in
many countries around the world, we are 'lucky' that way in the UK)
the other uses in cow milk production that don't typically exist with
alternatives a

The cows drinking water directly.
The irrigation of imported additional feedstuffs (concentrates /
ruffage).
The cleaning of dairy parlors (wash water).
The cleaning of milk storage equipment.
The cleaning of abattoirs.
Cleaning within bottling plants.

There is also the indirect consideration of the loss of rain in areas
that have had rain regularly previously due to the impact of cow
livestock methane on GW. Wamer air can hold (also not release) more
water than cold.

There is also the risk of dairy cow waste polluting existing water
sources / table from runoff during storms etc.

Cheers, T i m