A waste disposal firm has been fined more than £43,000 for dumping chemicals into the sewer system serving East Staffordshire.
Arrow Environmental Services Limited has to pay £43,750 - and £80,000 legal costs - for dumping illegal waste into Severn Trent's sewers.
Severn Trent runs sewage services for Burton and Uttoxeter households and businesses.
Arrow's prosecution is the third such separate court case which has seen judges hand out fines and costs together topping £100,000.
Severn Trent is highlighting the Arrow case in the hope that other firms will think twice before disposing of waste illegally.
James Jesic, managing director of production for Severn Trent, said: "Our customers pay for damage to the sewer network and the treatment works, so it’s important that we prosecute offenders in appropriate cases and take action to recover costs where possible.
"The limits we set to regulate trade discharges are calculated to make sure they do not adversely affect the capacity of our sewage works to efficiently treat sewage, so exceeding this consent is not only illegal, it can also damage the sewage treatment process and risks causing harm to the environment.
"In these recent cases, we’ve targeted prosecution at companies that have been found to have deliberately decided not to invest in appropriate protection measures to make sure they meet the strict limits in their discharge permits.
"They have prioritised cost over compliance with their environmental responsibilities and the effects on our sewage treatment works was significant, so we’re happy that the level of fines imposed reflects that."
According to Arrow's website, is is a specialist waste disposal company whose customers include "public sector organisations and local Government, through to some of the UK’s best-known brand names, which include the construction and demolition industry". The firm was prosecuted last month.
An spokesman for Arrow, which is based in West Bromwich, said: "Arrow Environmental Services Ltd is committed to ensuring that the incidents that occurred in 2016 are not repeated.
"We are working hard and are investing in systems to prevent any recurrence of those earlier incidents resulting in the breaches of our Consent to Discharge."
Severn Trent's investigation started due to issues at Rayhall sewage works, in the Black Country area, as it struggled to cope with substances entering the system.
The two previous separate prosecutions were brought against other companies in January.
The two firms also paid fines and court costs in excess of £100,000 for illegally discharging chemicals into the sewer system.
Mr Jesic said: "Although we are very happy with the outcome of these trials, rather than having to take action in court, we would much prefer to work together with businesses to prevent any breaches occurring in the first place.
"We hope that these fines will serve as a deterrent to other firms, and their customers, who are not doing what they should."