@Mauricio SalomI always start by bedroom and then adjust from there. That could be:
- laundry
- # of bathrooms
- private yard with sprinklers
Some scenarios which I've never faced but you might want to think about
- highly uneven number of tenants not accounted for with bedrooms (I wouldn't normally base on people because that can fluctuate with tenant change)
- highly uneven square footage not accounted for with bedrooms and bathrooms
- a tenant that keeps a greenhouse, etc (I actually did have this when I first started in rentals and was paying water. I had no clue how much it was costing me until he moved out - (probably a good $100/month) You may want to write some restrictions about this into your lease, maybe washing the car and anything above the normal
One thing my friend does is add an extra that she pays to avoid complaints. So if it's to be divided 4 ways she actually divides 5 ways and she pays the extra 1/5 and tells them that's to cover anytime someone might have used a little more than normal so they don't feel like they have to pay for someone else's use.
If I can give you one tip it is to ensure your toilets are in fantastic shape before you rent out the unit. Most tenants have no clue about toilets and unless it's an outright issue, they don't want to bother the landlord with a running toilet. This is a BIG problem in San Diego because the city only bills you every 2 months so if the worst case scenario you might have a running toilet for 60-70 days before you see that bill and freak out. I had a $2000 water bill that I never was able to collect from the tenant. So that's why I've started moving tenants to water responsibility. Oh and the annual 6% increases in the water bill are painful.
Not sure if you San Diegans have noticed but they seem to increase the MFR more than the SFR. I ran numbers for my duplex the other day and the tenants would have saved $20 had they been billed on SFR rates. Admittedly, my hope is not only to encourage tenant water conservation, but also to encourage engagement with the lawmakers and governing bodies. I send the tenants every notice I get about water rate increases.