When considering buying a new dish washer or just washing your dishes in the sink the initial cost of the unit on top of the cost of running it should be an important factor.
The benefit will be found on the size of family you have and how often you might use the dishwasher.
If you have a young family with a few children where everyone is eating all their meals at home the time to wash dishes all day takes away from other things you can be doing and with a young family there are always things that need to be done. On the other hand once they are old enough to reach in the sink you can start making them wash the dishes and that will free up some of your time maybe.
But in reality if you are thinking that time is more important than cost that is a big thing that you should take into account. Time is often more important than money when it comes to small things that eat up your daily routine.
Although many electric companies will send you literature about only running the dishwasher overnight that is for their benefit not yours. You will have to figure out when the best time to do it is and normally that is in the early evening hours after all the meals for the day have been eaten and maybe after the kids have had their baths.
If you are single or your children have left the home then the amount of washing you will be doing is minimal. If you are older and need the help then a dish washer can make sure everything is clean and to some extent it can even store your most used items so you won’t have to be searching for them in the cabinets.
On the other hand if you wash your items in the sink you can make use of a dish pan or a second sink bin if you have it to soak your dishes and then wash them later. You shouldn’t let them sit all day but a good half hour in soapy water will make them easy to rinse and then put away.
What do the professionals say about the cost?
If you were to read about this issue on a government website you would likely see that running a dishwasher that is high efficiency may actually cost less than washing by hand. Although you really have to wonder where their numbers come from and how they are generating the costs.
Personally after reviewing some of this information I am skeptical if the actual cost of running a dishwasher is less than washing by hand but they are probably not considering using a dish pan to soak dishes or the amount of water that every person uses.
Final Note
If you have a young or large family then the benefit is more the time you will save vs the money you will save and this is an issue.
In addition to water cost is the cost of dishwasher detergent which is much more expensive than hand washing soap.
Finally the cost of the unit and the cost of running it must be accounted for. If you are running it every day with a full load and the results of the cleaning is good then it is a benefit. If you find you do not have enough dishes to run it every day then you simply can not let dirty dishes sit for a day or two and expect them to come clean.
The choice is yours but if you stay with a basic but efficient unit the cost can be low and the benefit high.