Social media users have been left utterly baffled after a cleaning fanatic revealed a “secret compartment” hidden inside her washing machine.

Staci Hunt came across the covert card-sized holder on the inside of her Hotpoint drawer.

When she probed even further, she found a removable piece of plastic inside the slot.

She was initially scratching her head to work out why it was there and what it was for.

Now she’s got the bottom of what the sneaky slot is for she has shared the handy tips with others.

Social media users admitted they had no idea what it was for

She took to Mrs Hinch inspired Facebook page Mrs Hinch Made Me Do It to share her life-hack with others.

She wrote: “Did anyone else know this, I have only found out that that’s where it goes when you’re not using it."

Others said they had noticed the same compartment but admitted they had no idea what it did.

One said: "What does it do?"

Another wrote: "Checking our washing machine."

The covert compartment has a clever use

And a third added: "I use mine for my powder.. So I don't put too much in."

The feature, which is common among Hotpoint machines, is used to measure liquid or powder to avoid waste.

Users said they went to check their machines to see if they had the same feature - which many did without realising.

One person said: “I found this out the other week and I couldn’t believe it.

“I just kept it in the liquid draw for ages and always wondered why my washer wasn’t working as it should! I found as soon as I moved it my washer now smells fresh!”

"Think it must of been stopping the water and some product flowing out properly."

Another person, who’d also worked it out, wrote: “It’s to control the dosage measure when using liquid detergent."

Hotpoint manuals online have confirmed that the feature is to help measure the right amount of detergent.

The company says: "If powder detergent is used, place the partition into slot B - slot B being the aforementioned 'secret' compartment.

"If liquid detergent is used, it is recommended that the removable plastic partition A (supplied) be used for proper dosage."