It's just money down the drain, you know.

你要知道，这是白白丢钱。

《牛津词典》

To study English with Xindongfang is just pouring money down the drain.

跟新东方学英语就是把钱打水漂。

youdao

The mobile telephone is too old, paying to fix only lets you pour money down the drain.

这个手机太旧了，花钱修只会使你把钱付诸流水。

youdao

"These products are often referred to as upgraded accounts, but if you end up paying for an element you cannot claim on, it is money down the drain, " said Sheila Nicoll, FSA director of policy.

BBC: Bank rules seek to prevent account mis-selling

Irene can serve as our wake-up call, a reminder to look elsewhere for our energy needs: instead of pouring our money down the drain, funding oil despots overseas, our money should stay right here at home, where renewable energies can increasingly serve as an economic multiplier the likes of which Americans have never before experienced.

FORBES: Hurricanes Drive Home Appeal Of Alternative Energy Sources

Juliet Lyon, director of the Prison Reform Trust, said closing prisons and reducing prison numbers "offers major social and economic gains" but warned it "would be a gigantic mistake if the justice secretary were to revive the discredited idea of titans and pour taxpayers' money down the prison building drain" instead of investing in crime prevention, healthcare and community solutions to crime.

BBC: Seven prison closures in England announced