If you can, try to establish were the pipes run between the stopcock and your building, especially if you intend doing excavation work in the area.
Os yw'n bosibl, ceisiwch ddarganfod ble mae'r pibellau sy'n rhedeg rhwng y stopfalf a'ch adeilad, yn enwedig os ydych yn bwriadu gwneud gwaith cloddio yn yr ardal.