watering question

Hello everyone, so I'm growing in a greenhouse and I'm using a 55 gal drum with a small pump and a 1/2 line for the drip system . Problem is when the timer turns off the pump the gravity will just keep pushing the water until the barrel is empty. What can I use or how would I set up my system to prevent this?
Thanx in advance for any input I appreciate it

dig a hole for your 55gal drum. Make it so gravity wants to drain back to the drum.

That's a great idea

Just instal a check valve, it will only allow water to flow in one direction

^ Im sorry I miss interpreted it. Not a check valve, that is use for a different application. Use a sprinkler control valve.

Lol, just put a valve of your choosing between the barrel and your drip line.

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Thought of a valve. Mechanical valve won't work cuz I need it automated and an electric al 1wouldn't really work cuz I'm using a pump that's on a timer. Guess it could work I was just worried about the pump coming on and the valve not opening up in time.