This average supply figure is then to be compared against the average of how much drinking water the utility produced based on the last 3 years.
Yna, bydd y ffigur cyflenwad cyfartalog hwn yn cael ei gymharu â’r cyfartaledd o faint o ddŵr yfed y mae’r cyfleustod wedi’i gynhyrchu ar sail y tair blynedd diwethaf.