The rules in more detail:

Septic tanks and Sewage treatment plants must be registered with Natural Resources Wales (NRW).

If your system discharges to ground, you can use a septic tank or Sewage Treatment Plant via a drainage field. If it goes to surface water, you must use a Sewage Treatment Plant.

Private sewage systems in operation before 6 April 2010

If your private sewage system was in operation before 6 April 2010 and met the standards in place at the time you will be able to register if you’re discharging to a watercourse even if you’re near sensitive sites or species or in an area with a public sewer. However your discharge must be from a Sewage Treatment Plant, not a septic tank.

If you’re discharging to ground (a drainage field), you will only be eligible for a free registration if you are not located within a groundwater Source Protection Zone 1 or within 50m of a well, spring or borehole that is used to supply water.

If your sewage system came into operation after this date, you will need to comply with the conditions below to comply with regulations.

Before you register

Ensure your private sewage system is far enough away from sensitive sites, habitats or species

If you are making a discharge to a watercourse the discharge must:

• only be made to a watercourse that normally contains water throughout the year – it cannot be to an enclosed lake or pond
• not be within 500m of a Special Area of Conservation (SAC), Special Protection Area (SPA), Ramsar site, Biological Site of Special Scientific Interest (SSSI), freshwater pearl mussel population, bathing water or shellfish waters
• not be within 200m of an aquatic local nature reserve
• in tidal areas, be located below the Mean Low Water Spring (MLWS) tide limit

If you’re making a discharge to ground (to a drainage field) the discharge must:

• not be located within a groundwater Source Protection Zone 1 or within 50m from a well, spring or borehole that is used to supply water
• not be within 50m of a Special Area of Conservation (SAC), Special Protection Area (SPA), Ramsar site or Biological Site of Special Scientific Interest (SSSI)
• not be within an ancient woodland

Ensure the manufacture and design meet standards

You should ensure that the sewage system meets the required design and manufacturing standards and is appropriately located.

You should have any necessary planning and building control approval for the treatment system and discharge.

The sewage system needs to comply with:

• BSEN 12566: 2000 Part I prefabricated units
• BSEN 12566: 2007 Part IV for septic tanks assembled in situ from prefabricated units
• BSEN 12566: 2005 Part III for package or site assembled domestic sewage treatment plants

For discharges to ground the discharge must be to a drainage field installed in accordance with the British Standard BS6297:2007+A1:2008.