I have tried unblocking my external drain, blocked by grease, by pouring boiling water with sea salt it melted the grease straight away and i collected all the grease that came to the service with a sieve i then used a rod to ensure the chamber was clear and then cleaned all more hot water and then cold water saved me about £! Burnet road, sweet briar industrial estate, norwich nr bs. Thanks for printing! don't forget to come back to delta plumbing for fresh articles! We.