East Staffordshire Borough Council offers a grant each year to help allotment associations buy tools and equipment used by everyone on the site. This grant is currently £8.63 per plot. Further information can be obtained by contact the Allotment Officer on 01283 508385 or email firstname.lastname@example.org.
How about asking your plot holders if they would like a water butt? This would help reduce your water bills and you could recoup the cost through the grant.