Four oz beers of your choice! To ensure our clients receive a high standard of workmanship, experience and professionalism, our company is accredited and monitored by several trade and industry bodies. It's so great to be able to keep drains clear without toxins! Watersafe approved plumbers are certified by our national accreditation body, with specific training in the uk water fittings regulations and byelaws. Can they provide you with local referrals? Expanding foam cleans.