If you have a septic tank or private sewage treatment plant, it is important that you understand your legal obligation. There are may thousands of houses in the country that rely on a septic tank or private sewage treatment plant, trouble free and without inconvenience.
Maintenance and conforming to regulations are the key factors to a trouble-free private sewage system for more information take a look at the statutory guidance on Small sewage discharges in England: the general binding rules
https://www.gov.uk/government/publications/small-sewage-discharges-in-england-the-general-binding-rules
If your property has a cesspool please look at the government guidance rules here
https://www.gov.uk/permits-you-need-for-septic-tanks/you-have-a-cesspool