Today I have been keeping track of my water usage, and also trying to economise on it as if it were precious. It came to about 1.3l for drinking, 0.7l for cooking and 1l for washing, or about 3 litres in total (about 3/4 of a US gallon).

Drinking includes 3 coffees, 2 glasses of juice and some milk with breakfast cereal. I had my usual sedentary life-style, as if confined to the house by quarantine.

Cooking was mostly spaghetti for lunch and rice for tea. Most of that water ended up in the food. About 200ml was lost to evaporation. There was also about 250ml of "grey water" left over which I've counted as waste, but which is quite drinkable (I used some for one of the coffees). Rice is easier to cook in low water than spaghetti.

Washing included my hands, face and teeth, and also plates, cutlery etc after cooking. I was aiming for a low but realistic level of hygiene, sustainable for a few weeks. I'm pretty good at getting plates clean with minimal water. Hand-washing is much harder. Paper towels helped.

I didn't include water used in flushing the loo. That would have seemed very wasteful of drinking water. In an emergency I'd hope to either use wild non-drinking water, or else make other arrangements.

I didn't include any clothes or hair washing. I figure that's realistic for a few weeks, but not really long-term. I didn't have any first-aid needs. My pets can find their own water.

I live alone. I suspect it could be hard to get other people to adopt the same level of water-discipline. 3 litres felt quite extreme; 4 litres per day might be a better rule of thumb for me. As it happens, I have about 50 litres stockpiled, which is about the limit of what is convenient for me. I also have about 5 rolls of paper towels stockpiled, and I think now I will increase that - it's easier to store because it's lighter and doesn't expire.

Good experiment! 3 litres is hardcore. Add any physical labour and that jumps to 4. If it's a hot climate it's probably 5+.

Do you have any opportunity to collect rainwater (or condense fog ;-) in your location? That could boost supplies for personal washing, tea-making, and flushing.

Recover your grey water by using a solar still. Harvest moisture from the ground, leaves, etc. in another solar still.

Depending on what you are putting into it, grey water can be used to good effect on your plants.

It seems to me that putting grey water into your toilet tank and using it to flush...turning it into black water could get 2 uses out of the same water.

The amount of grey water produced by cooking was pretty small, and I don't see why you couldn't just drink it.

Flushing my loo needs about 9 litres (I just measured it) so I'd need really copious supplies to even consider it.

grey water is also produced by washing...that water isn't drinkable as it has soaps, detergents, and potentially human pathogens in it (though it can be treated, technically).

Also, you can save water in your toilet by adjusting the float so there is less water in the tank between flushes. My toilet is a low profile, high efficiency model. I think it uses 5 or 6 L but I'd have to check to be sure.

You can also save on flushes by not flushing as often. Only flush for #2 and you can save a lot of water.

In the wilderness doing any kind of work I think 4 to 6 litres per day is the level of water consumption we should consider the norm for planning purposes.

This article may be of some interest: http://boreal.net/Research/water-balance.shtml

You could get a well.

I have a well. But it's bloody awkward in my BOB.

:-)

That is a great experiment. I gather you are just looking at expenditure as if there was no more potable water in your area.

Have you or will you attempt to find water resources and purify them to refill your stock while your using your BOB? In your area, situationally dependent, I think it would be highly important to find replenishment, either through nature or assistance.

I imagine that you would have tablets, iodine or some sort of filter in your kit at home or on the move.

I suppose lastly, and it may be off topic, but when a disaster is looming or just past and your staying at home, fill up your bathtub for an additional 30-50 gallons of useful water that would already be stored in your pipes and tank.

I was interested in the "shelter in place" scenario, especially of the kind where I can't actually leave the house (eg because of quarantine).

It might be, if it had references. As it is it makes bold, scientific-sounding statements with nothing to back them up. For example, "300ml of water is sent to the urinary and digestive tract for each 1L consumed. 500ml is sent to the urinary and digestive tract when you consume caffeinated beverages, such as coffee." This contradicts what is written on other sites, eg from http://www.pponline.co.uk/encyc/caffeine-dehydration.htm:

• A similar study considered the effects on hydration of different levels of caffeine consumption (5). Eighteen healthy men consumed each of four different drinks: pure water, water plus cola, water plus diet cola and water plus coffee. Body weight, urine output and blood samples were measured before and after each treatment, and there were no significant differences in the effect of the various combinations of beverages on hydration status.

I'm afraid the Boreal article, as written (were you the author?) doesn't carry as much credibility because it doesn't describe original experiments or cite references to such. And of course, my own experience wins. I have measured what I drink on other occasions, living my mundane working life, and it usually comes to about 1 litre per day.