Up to 94,000 homes could be left without bin collections if workers decide to reject their employer's latest pay offer and take strike action.
Bin workers voted overwhelmingly for strike action on Wednesday, saying that they were offered a real term pay cut from their employer, Veolia - leading the company to return with a new offer.
Workers say they deserve more as the contractor has received more funding from the council this year.
If workers vote again to strike, it could take place as early as 27 April.
Veolia runs bin collections on behalf of West Northamptonshire council.
The council increased its funding to Veolia by 5.5% this year, something that the GMB union said had not been reflected in workers' wages.
A spokesperson for West Northamptonshire council confirmed that the money it pays Veolia had increased, but that the workers' wages were decided by and paid for by Veolia.
Dave Warwick, GMB organiser, said: "Northampton town now faces a massive bin strike because of bosses' penny pinching. The council has given Veolia a big funding increase to battle inflation, but the company won't pass any on to workers.
"Now they must deal with the consequences – dirty streets and huge disruption for the residents of Northampton.
"It’s not too late to stop this strike - a decent pay offer would get workers back round the table.”
A Veolia spokesperson said in a statement: "Veolia has previously received notification from the GMB of the ballot outcome.
"As part of the ongoing negotiations and process, we have made two improved pay offers and we are now awaiting feedback from local members on our most recent offer.
"We remain committed to finding a resolution for our staff and avoiding any disruption to residents’ collections.
"It is important to point out that any contract uplift takes into account fuel, inflation as well as employment costs.”
There will be a further meeting on Tuesday to discuss next steps.