Re: Anyone have success washing with just cold water?
There are four components to clean laundry: heat, water, detergent, and agitation. If you remove one of those (heat), you're going to have to compensate with better/more water, better/more detergent, and better/more agitation. Now, you also have hard water, so that is bad for clean laundry. In order to make this work, you're going to have to choose the cycle with the most agitation and choose a very strong detergent, and likely some boosters.
Someone above said she can do this with Tide Coldwater detergent. This detergent has more enzymes and a different surfactant that make it work in cold water. However, these different cleaners can be more irritating to some people (I have found reviews of it for all laundry, not just diapers, in which people said it caused rashes, but others loved it.) It might be an option for you, or it might cause rashes. In any case, it is a very strong detergent.
There are cloth diaper detergents that are meant for hard water, like our own Lulu's in the Fluff. If you choose a natural detergent, make sure it works in hard water.
If you have a lot of thick microfiber diapers or inserts, you may have to bleach those more often because microfiber threads look like a snowflake, and crud builds up inside the "arms" of the snowflakes. If all your diapers are loose cotton prefolds, then you shouldn't have as many problems.