Outdoor Drainage Discussion Preparation Checklist

Go outside during heavy rain rather than afterwards, and note where water arrives, where it travels and where it finally stops.

The path water takes is only visible while it is running; once the ground has dried the evidence has gone and only guesswork remains.

Mark on a sketch every place where water stands after rain, and note in general terms how long each one takes to clear.

Where water sits and how stubbornly it sits are different pieces of information, and both matter to whoever looks at it later.

Note whether water sitting in a hollow drains away into the ground or simply lingers until it evaporates.

Whether ground accepts water or refuses it points a professional in very different directions from the outset.

Record where the lawn feels spongy underfoot during the wetter part of the year, even where there is no visible puddle.

Persistent softness without pooling often indicates saturated ground rather than a surface water path, and it is worth distinguishing.

Photograph silt lines, washed gravel and scoured soil, which show where water has run fast even when everything is dry.

These marks are a record of the worst events rather than the typical ones, which is exactly what a drainage discussion needs.

Note whether water crosses a path, a doorway or a threshold on its way through the garden.

Water crossing a route used by people is a practical problem as well as a technical one, and it should be stated explicitly.

Where water should be directed, and what capacity would be needed, is a design matter for a qualified drainage professional.

Follow each downpipe to the ground and note whether it enters a gully, a chamber, a pipe or nothing at all.

A downpipe discharging onto open ground is common and changes the whole picture of how wet a garden becomes.

What a downpipe connects to below ground can only be established by a qualified professional, never assumed from the surface.

Check whether any gully is choked with leaves, silt or moss, and whether it visibly overflows during heavy rain.

An overflowing gully is an observable symptom that helps distinguish a maintenance issue from a capacity issue.

Record whether a downpipe discharges onto a surface that then carries water back towards the house rather than away from it.

The fall of the surface receiving roof water matters as much as the pipe itself, and it is visible during any downpour.

Watch whether gutters overflow at a particular corner, and photograph it while it is actually happening.

A repeated overflow point localises the problem and saves considerable investigation later.

Write down where the roofs of a shed, garage or extension shed their water, since these are frequently overlooked altogether.

Outbuilding roofs contribute a surprising amount of water and often discharge straight onto ground beside a wall or a path.

Consider whether any water butt overflow has anywhere sensible to go once the butt is full during sustained rain.

A full butt simply returns the roof water to the ground beside the building, usually at the worst possible moment.

Find and photograph every drain access cover, gully grate and surface channel in the garden, including any hidden under planting or decking.

A complete list gathered patiently over time is usually better than one made during a single site visit in the wrong season.

Do not lift a cover or attempt to trace a run yourself; ask a qualified drainage professional to establish what each one serves.

Mark which covers you suspect are surface water and which you suspect are foul, and label your notes clearly as a guess.

An owner's impression is a useful starting point provided it is passed on as an impression and never as an established fact.

Record whether any channel or drainage line crosses a route you use regularly, and whether it sits flush with the surface.

Channels that have settled or lifted create trip points and also stop working as intended, so both aspects are worth noting.

Note whether a chamber sits at a low point in the garden or has been buried beneath a later surface.

Chambers covered over by subsequent work are common in older gardens and are far easier to find before excavation begins.

Write down whether anything appears to drain into a ditch, a watercourse or a bank at the edge of the plot.

Discharge at the plot edge raises questions well beyond the garden and needs identifying early rather than late.

Ask the relevant authority what applies to any discharge towards a ditch, a watercourse or a highway drain before it is relied on.

Note where a soakaway is believed to be, and record clearly that this is what you were told rather than something you have seen.

Distinguishing hearsay from observation prevents a rumour hardening into a design assumption nobody has ever checked.

List every hard surface you have now and note whether water runs off it or soaks through it, as far as you can observe during rain.

Gravel, paving and decking behave very differently, and an owner watching them in rain can describe that better than any drawing.

Consider how much extra hard surface the project would add, and note this as a question to raise at the earliest opportunity.

Adding hard surface changes where water goes, and raising it at sketch stage avoids reworking a layout after paving has been laid.

Whether additional hard surface needs consent or a particular drainage approach must be confirmed locally with the relevant authority.

Note where an existing surface appears to fall towards the house rather than away from it, and photograph the evidence during rain.

This is one of the most consequential things an owner can spot, and it is obvious while raining and invisible when dry.

Record which surfaces stay wet longest and whether that matches where they sit within the overall fall of the garden.

A surface that stays wet in a high spot suggests something quite different from one that stays wet at the bottom of a slope.

Write down whether any existing surface may have been laid over a former soakaway, ditch, pond or filled garden.

Covering an old drainage feature is a frequent cause of water appearing where nobody expects it.

Consider whether an area of lawn is likely to be replaced by something that sheds water considerably faster.

Turning absorbent ground into shedding ground moves the water elsewhere, which is the point at which a professional view is needed.

Look at where neighbouring ground meets yours and note whether water visibly arrives from a plot sitting higher than your own.

Water crossing a boundary is a different problem from water falling on your garden, and conflating the two wastes everybody time.

Water crossing a boundary is a legal as well as a technical matter; take suitably qualified advice before altering anything at that edge.

Note whether a neighbouring downpipe, drive or paved area appears to discharge towards your garden during rain.

This is observable from your own side and is worth recording carefully, with dates, before any conversation takes place.

Record whether a road, footpath or bank above the plot sends run-off in your direction during heavy rainfall.

Highway and path run-off involves parties beyond your neighbours and needs identifying early so the right questions get asked.

Write down whether the plot sits towards the bottom of a wider slope, even where your own garden looks reasonably flat.

A flat garden at the foot of a catchment receives water from well beyond its boundaries, which explains many stubborn wet areas.

Note any history of water arriving unusually, and gather what previous owners or neighbours have said about it in their words.

Long-term local memory frequently captures events that no recent record shows, and it is worth writing down before it is lost.

Consider whether anything you plan could send more water towards a neighbour, and flag that as a question rather than a conclusion.

Raising this yourself early is far better than having it raised for you once work is under way.

Note where water stands against the base of a wall after rain and photograph it while it is still there.

Recording the position and extent of pooling at the building gives a professional a concrete starting point rather than a description.

Damp at the base of a building must be assessed by a qualified professional; nothing observed from outside establishes its cause.

Record whether any airbrick or vent sits close to a place where water pools during heavy rain.

The relationship between pooling and ventilation openings is exactly what a professional will want to look at.

Look for water marks, silt or a tide line on a threshold, showing where standing water has previously reached.

Marks left behind record the height water has reached before, which no single observation during rain can tell you.

Write down whether any internal damp appears in a position matching a low point or a wet area outside.

Noting the coincidence is useful, but the connection is a professional judgement rather than an owner's conclusion.

Note whether a raised bed, gravel or soil currently sits directly against the house wall at any point.

This is common, easy for an owner to see, and always relevant to a conversation about water at the building.

Record where water discharges close to the building and whether it appears to soak straight into the ground there.

Concentrated discharge next to a wall is worth recording precisely, including which downpipe or surface it comes from.

Write down every occasion you know of when a drain has blocked, backed up or overflowed on this plot, and where it happened.

Repeated trouble in one place is a strong signal, and it is information only the occupants of the property hold.

Gather anything a plumber or drainage engineer has told you previously, recorded in their words rather than your summary of them.

Summaries lose the qualifications and uncertainties that make a professional statement useful to the next professional.

Ask about any drainage work carried out before you arrived, if a previous owner or a neighbour has ever mentioned it.

Undocumented earlier work explains many otherwise puzzling arrangements found in the ground.

Record whether the property shares any drainage run with a neighbouring plot, as far as you have been told or can infer.

Shared runs are extremely common in terraced and semi-detached property and change who is responsible for what.

Shared and public drainage runs carry particular obligations; confirm locally with the relevant authority who is responsible for each.

Find out whether the garden has ever flooded and how far the water reached, marking the extent on your sketch of the plot.

The extent of a past event is more useful than the fact of it, and marking it on a plan makes it usable by somebody else.

Write down whether the plot appears in any flood information you have seen, and treat that as something to confirm rather than a conclusion.

General information about an area is a prompt for a proper check, not a finding about your particular garden.