Complex sentence: While the share of those with access to an improved water source is much higher than for sanitation (86%), the quality of service is poor and most users that are counted as having access receive water of dubious quality and only on an intermittent basis.
Split into simpler sentences: While the share of those with access to an improved water source is much higher (86%), the quality of service is poor. Most users that are counted as having access receive water of dubious quality and only on an intermittent basis.