The phrase "allowed to drain" is correct and usable in written English.
It can be used in contexts where something is permitted to be emptied of liquid or to lose energy or resources.
Example: "After the rain, the garden was allowed to drain to prevent waterlogging."
Alternatives: "permitted to empty" or "authorized to release".
Also, if allowed to drain completely, they can short-circuit and make recharging dangerous.
The topping for an angel cake calls for nonfat yogurt that has been allowed to drain for three hours.
A vet examined the dolphin yesterday morning and soon after high tide at 2pm, the harbour was allowed to drain, leaving the dolphin in a shallow pool.
The soil had been saturated with water and then allowed to drain freely for about 5 10 min prior to planting.
The mixture to be separated is added to the top of the column and is allowed to drain onto the stationary phase.
The afternoon before the start of the dry-down, soil was fully saturated and the pots were allowed to drain overnight.
A team of journalists who observed the decontamination work in the region last month added: "Water sprayed on contaminated buildings has been allowed to drain back into the environment.
But this type of credit must only be offered to those that can afford it and payday lenders must not be allowed to drain money from a borrower's account".
Did the star of Nosferatu, the 1922 horror classic, strike a bargain with its director FW Murnau - to appear in his movie in return for being allowed to drain the entire cast and crew of their blood afterwards?
This experiment utilized split-root rhizotrons with two separate chambers, allowing for half of the root system of each plant to be flooded while the other half was allowed to drain.
In another set of experiments, in which inflow was stopped and the fluid was allowed to drain out of a single open hole, the outflow rate was in accordance with Darcy's law for one-dimensional flow in the vertical direction until the fluid height above the hole fell below a certain limit.
