Having had caravans, we were used to the meagre bowl offered with small plasticy tap. Building the van ourselves was the opportunity to fix that and have 'proper' facilities. So we looked in B&Q, Homebase and Screwfix for what we wanted, and eventually bought a bargain full size tap, sink and drainer from Screwfix. This came with 40mm drainage, a deep stainless steel bowl, and a chrome metal tap with single leaver control.