You may want to look at the tags on the water heaters. The energy saving water heaters are very well insulated. I have a 65 gallon in my home, we have 4 adults with 2 wash machines, one dishwasher and at night we never run out of water, two showers at a time at night and in the morning. The 50 gallon would not have been big enough for us. The annual cost was not that big of a difference to worry about. If we put a 50 gallon in it may have not been able to keep up. Good luck. G