I posted a similar problem a few years ago.

First update to the latest 1.2 version (you probably already did).

Then set the Equis labor pool for water to be the 'highest' priority.

Occasionally you will lose fountain access if any one of the 3 equis needed to run the fountain get shuffled to some other task. And even with full employment, sometimes they will never get fountain access, even if the fountain is very near, because they are too busy trying to get luxury/basic goods, or food.

If they are taking too long to walk to those locations, it can mean they never get time to get water.

now to my knowledge that was fixed in v1.2, meaning they get water before any other resource.

plebe housing, which usually only need wells (not fountains) to expand to max.

Plebs will go to medium insulae without fountains, but they need them to go to large insulae.

Equite labour shortages can indeed cause fountain access problems, but it is more likely to result from the shrinkage of reservoir 'coverage' than from having too few fountain workers. If the fountain is right on the edge of the coverage area it might only take a couple of workers short in the reservoir to leave the fountain 'high and dry'.

Citizens do prioritize water, but only when their stocks are sufficiently low. If they are already out doing something they might consume their residual stocks before they get chance to get back and go for more water.

Welcome to Caesar IV Heaven Roxxsmom

Yes, I always set the labour priority for water to Highest too; it's a disaster if you are short on workers and then more start to leave. Also, as Trium and xenxander mentioned, your citizens might be busying getting food or goods if the markets are too far away.

[This message has been edited by kach (edited 03-21-2010 @ 04:24 PM).]

Most of my plebe houses are upgrading to the highest levels without fountain water (only wells), which is what I remember them doing a few years back when I played. This seems to be a new issue and sporadic, so I am not sure what the issue is. In the interest of making maximum use of the space available, I generally do not set up my cities with reservoirs near the plebe housing blocks.

The issue with the equite/patrician house closest to the fountain occasionally devolving and not upgrading again because it "needs access to fountain water" seems to be happening even with extra equite workers available, so would making water services the highest priority make a difference in this case? The little icon suggests that the house is receiving uninterrupted access to fountain water. Do the people living in the house sometimes just "forget" to go to the fountain because they are going too many other places?

The correct patch is 1.2. You should see this version number at the top right of the main menu screen.

If the pleb housing is at Large Insula, then the occupants have access to a fountain. If you click on the house, you will see that the well icon has been replaced by a fountain icon. Your citizens will ignore the wells and get water from a fountain (assuming that there is a fountain somewhere connected by road to their house). The fountain doesn't have to be nearby - it doesn't give range coverage like services buildings do. It acts like a market, the citizens go to the fountain.

If your citizens have to travel a long way for food or for basic or luxury goods, they may run out of water before they return home, and the houses will devolve. You could try clicking on the icon that represents the people in the house (I think there are usually two people, but I can't be sure). Follow them around and see where they are going. Maybe there isn't enough food in the market and they spend all their time just getting wheat one at a time.