Water, Drainage and Ventilation in Historic Places of Worship

If you're planning to install new toilet or kitchen facilities, these will require water, drainage and ventilation. You may need an archaeological assessment and statements of significance and need to establish the impact of installations on your building and any underground archaeology.

Designing new schemes

Subject to archaeological advice, we recommend routing pipes underground rather than directly through walls.

If you're thinking about installing new toilets, composting or macerating lavatories can remove or reduce the need for drainage trenches.

Foul drainage provision for new facilities

It's always preferable from an environmental point of view to connect to mains drainage where possible. If you're considering alternatives, then the site specific setting must be taken into account to ensure the receiving ground is suitable for any discharges. Site suitability is often complex and discussion with your local environmental regulator is always recommended at design stage.

Trench arch systems

In rural buildings where use is not heavy and where space allows, you may be able to consider a trench arch system, which can avoid deep excavation and complex drainage.

All trench arch systems (including those already installed) require a permit from the Environment Agency to discharge to ground. We recommend that you contact your local Environment Agency office for advice if you're considering or have such a system.

Further information is available on the GOV.UK website.

In addition to these environmental issues, there are important archaeological aspects to bear in mind. You can find further information about the impact these systems can have on archaeological remains in churchyards in our report along with our recommendations for considering trench arch systems.

These include the following points:

  • Whilst a mains drain connection is preferable, it should be considered that making this connection may also have archaeological implications.
  • If you are considering a trench arch system, we recommend you undertake an archaeological assessment of the potential of the churchyard at an early stage. This will ensure that you can take the information it reveals into account when developing the specification.
  • The assessment should consider whether you need archaeological fieldwork, like evaluation, before you get permission or begin works.
  • Trench arch drains are best located away from archaeologically sensitive areas of the church. Such avoidance is made possible by understanding the archaeological potential of the site.
  • You should not assume that you will not find significant archaeological remains within the top 0.5 metres, just because this is above current burial depth.

It's often possible to provide ventilation for toilets and kitchens discreetly. For example, in the upper stages of towers, by introducing mesh grilles into windows or flush cast-meal or stone-tile grilles into walls, or by setting the vent-pipe back in the wall and fitting stone or slate louvres.

We recommend that you avoid drilling new ducts through historic masonry and installing external fan units and cowls.


A degree of dampness is common in the walls of old churches, especially where external ground levels have risen over time.

If you are considering work to remedy damp, we do not normally recommend ground lowering, which is sometimes associated with laying drains. This is because ground lowering can damage archaeological features, foundations and wall surfaces, and may lead to excessive drying out with subsequent cracking and even subsidence.

The best way for you to manage damp is by regularly clearing gutters and downpipes, ensuring good ventilation and allowing for permeability in the wall surfaces through the use of 'breathable' mortars, plasters and finishes. The best way to get rainwater away from your building is through downpipes to gulleys and soakaways, which keep water away from the walls of the building.

Please also see our pages for more information on maintenance.