In SimCity Deluxe, why do my Sims constantly ask for water?

Apparently there's nothing wrong with the water-supply and as comments to the question suggest, a city of this size should never require that many pumps and water-towers. So I'll try to answer this question myself and claim that it's a bug.

I did some searches and as it seems I'm not the only one with this problem. Here's a forum post and here's another one suggesting that there is indeed a bug regarding water supply. So I guess the only hope is waiting for an upcoming patch to fix this.

You need to renew the old pumping stations, the old ones get inefficient and lose capacity. Agree, it is hard to play with this bug or issue.