Domestic water demand based on the building use type

For rough numbers you could use the attachment, pages 14ff. The attachment is for sewer flows to a septic tank, which is what we would typically use unless we could get better information. I assume domestic water in more or less equals sewage out, unless there is a special case. You could also check the state or local plumbing code, but you would have to make assumptions for fixture count. You'll have to convert the restaurant square footage into number of seats and the pharmacy square footage into number of bathrooms.

Have not seen any published resources that I can point you to. There is so much variance in building design that you may have to go into more detail to obtain the data you seek.

An architect may have a rough idea based on square footage and end use but could give you a more accurate answer with an actual building design where the number of fixtures can be identified. Also with the trend toward sustainable/green building, more water conservation and recycling measures will affect water demand.

You can estimate the restaurant flow at 10 gallons per person per day. Assume 3 meals per hour. ONe hour at lunch. Maybe 3 hours at dinner. Each person will need 6 to 8 square feet per seat.

The pharmacy restroom would be about 100 gallons per day total.