On Wednesday, the High Court approved the Â£84m takeover by utilities giant Severn Trent.
The shareholders of the Wrexham-based company, who called it a "David versus Goliath" dispute, had planned to appeal.
Shareholders said they had dropped the legal challenge so uncertainty "can come to an end."
Dee Valley Water employs about 180 people and has 230,000 customers across the Wrexham and Chester areas.
Severn Trent Water said it plans to build on Dee Valley's customer service record and make a "significant" investment in the region, but some staff and customers opposed the move amid fears for jobs and an increase in bills.
Shareholders had been granted leave to appeal the ruling and had until Monday to launch their application.
In a letter, seen by BBC Wales News, shareholders said the legal process had taken up a "significant amount of time and energy".
"After much consideration, the opposing shareholders have decided that it is now appropriate to end their legal challenge to the takeover so that the uncertainty which has been hanging over employees and our local community for some time can come to an end," the letter reads.
The letter adds: "Although this is not the outcome that the opposing shareholders would have wanted, we sincerely hope that Seven Trent Water can retain the local workforce and suppliers.
"We wish the company every success under its new ownership in continuing to provide the high levels of service to the community we care so strongly about."
Plaid Cymru AM for North Wales Llyr Gruffydd said jobs had to be safeguarded in the area.
He said: "Before the takeover, some promises were made by Severn Trent about jobs and I now call on the company to maintain a presence in Wales and to ensure that the skills and services provided in Wales are not lost."
Opponents of the takeover of Dee Valley Water have dropped their appeal.