If there is plumbing, water, and electricity already installed, it can cost between £100 and £250. It becomes increasingly expensive if the installation requires new plumbing or electricity to be rewired to the place the washing machine will fit. In that case, the cost can be between £500 and £1,000, depending on the difficulty of the installation. If electricity needs to be installed or rewiring is necessary, this needs to be done by an electrician.