Hi Lone,
re the water source I don't purposely put anything out for my bees. I have a wading pool out in the yard for the dog to play in which I see bees at every now and then but I generally let them find food and water them selves.
The hive you have should have been split at least 3 months ago so if it was going to fail it would have already. I don't think you'll have any problems with it and as they are zero maintenance, just place it somewhere and ignore it :)
Another pest I should have mentioned is ants. I don't think ants will destroy the hive but they are unsightly and the bees will spend time fighting them off. To combat the ants I mount my hives on star pickets and grease the pickets so the ants cant climb up.
Be mindful that it takes a lot of time and effort for these small bees to seal the hive after you open or split so limit opening it up as much as you can. As I said they are pretty much zero maintenance. I might open mine 3-4 times a year which includes splitting. If you do split or pop the top for a look, make sure you tape up the join to help keep out any bugs while they reseal.
Here are some pictures I just took for you.
This hive was split late last year. The picture is just to show what my boxes look like. They are made from cypress pine for good durability and insulation. The boxes are in 3 pieces, Lid, top box and bottom box/base.
Notice the resin between the top and bottom box. The boxes I made weren't very square but they sealed the gaps.
This image is to show the thickness of the timber used to build the box. The thickness is a little over kill for around here but is good for places with high or low temperatures.