Children at NurtureStars Pre-school in Toa Payoh found that the taps in their school were "spoilt" yesterday. The pre-school's taps were shut off for four hours, and the 90 children could only use water from the two 1.5-litre bottles that they each brought to school. The children were taking part in a water-rationing exercise, organised by the pre-school in partnership with national water agency PUB. The exercise is part of a month-long series of events in conjunction with Singapore World Water Day. Dr Amy Khor, Senior Minister of State for the Environment and Water Resources, visited the school yesterday during the water- rationing event. The pre-schoolers are among more than 14,000 students from 45 institutions - including 34 pre-schools - taking part in water-rationing exercises this month.