Robert Walker was arrested following a police raid at his then home in Clydebank last August.
No drugs were found, but officers instead discovered five barrels of a much sought after mixing agent known as 'bash'.
A judge heard how the huge amount of 'bash' seized could be used to adulterate £8.75m of heroin.
Unemployed Walker, 29, pled guilty at the High Court in Glasgow to being concerned in the supply of heroin.
He was jailed for two years and three months by judge Lord Turnbull, who said: "Rather foolishly you were providing help to drug dealers engaging in their trade of drug supply.
"Your contribution was providing a safe storage for a commodity which was valuable and of importance to these individuals who you knew to be drug dealers."
Police raided the home Walker shared with his father and brother in Mossgiel Drive, Clydebank, on August 22 last year.
Three black bags, each containing a wooden barrel, were discovered in a garden shed.
Another two barrels were then found in the back garden.
Walker was not there at the time, but he was detained at another property in Clydebank days later.
Prosecutor Bill McVicar told the court: "Walker stated he had agreed to store the barrels of powder for other individuals for £400.
"He said that he did not know what it was, but knew that it could be used to mix with drugs."
The powder - a combination of caffeine and paracetamol - weighed a total of around 125kg (275lbs).
The court heard the mixture was a "common adulterant" used to bulk out and reduce the purity of heroin.
Police said the powder could not have had "any legitimate purpose".
Mr McVicar added: "This mix has become so desirable that a 'grey' market has developed to obtain it."
The advocate depute said the £8.75m figure was the "potential financial impact" of this quantity of 'bash' on the illicit drugs market.
Defence counsel Ronnie Renucci told the court that Walker was "shocked at the amount" of powder.