Blocked drains and other drainage and sewerage problems are usually the responsibility of property owners, water and sewerage authorities, and highway authorities.
The drains, and internal pipes, within a property that carry household waste are normally the property owner's (or the landlord's) responsibility up until the boundary of the property where they connect to public sewers. There will often be a company maintained manhole at that point.
Your sewerage company can advise you about investigations and help available in the event of blockages or flooding. They may advise you of charges that may apply for carrying out work to private drains.
Gullies and drains on public highways are usually the responsibility of Hertfordshire County Council.
Sewerage companies are responsible for the public sewers. These are usually in roads or public open spaces, but may run through private gardens.
The sewerage company has a right of access to these sewers for maintenance. If the company carries out work on sewers on your land they must follow a code of practice, which is available from the company.
Anglian Water is the sewerage company for most properties in North Hertfordshire, though some areas in the southern part of the district are covered by Thames Water. You can confirm who your sewerage company is by checking your water bill.