Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: We should realize that using a lot of water for wudoo’ or ghusl is included in the words of Allah (interpretation of the meaning): “and waste not by extravagance. Verily, He likes not Al-Musrifoon (those who waste by extravagance)” [al-An ‘am 6:141]. Hence the fuqaha’ (may Allah have mercy on them) said: It is makrooh to waste by extravagance even if one is on the bank of a flowing river, so how about if water is drawn by mechanical means?
Wasting by extravagance when doing wudoo’ and otherwise is a blameworthy action.
Sharh Riyadh as-Saaliheen