These investment programmes are provided to the economic regulator Ofwat every five years and are challenged for both provision of the service provided and the affordability of the plans.
Darperir y rhaglenni buddsoddi hyn i'r rheoleiddiwr economaidd Ofwat bob pum mlynedd ac maent yn cael eu herio o ran darpariaeth y gwasanaeth a gynigir a fforddiadwyedd y cynlluniau.