The town recently tightened water restrictions from Level 3 to Level 4. Under Level 4, outdoor watering with sprinklers or irrigation systems is only allowed on Tuesdays and Saturdays from 7 to 10 p.m. Watering with hand-held hoses with nozzles and watering cans is allowed any time, as is car washing. The restrictions are in place until further notice. The announcement came just three days after the town had moved to Level 3 restrictions. Both actions were triggered under state regulations when water flow on the Ipswich River dropped below specified levels. The state adopted the regulations, which apply to all communities that draw water within stressed river basins, to protect those rivers. The two wells and two reservoirs that Danvers uses for its water supply — the system also serves Middleton — are all in the vicinity of the Ipswich River.