How many sinks are there in the UK?

A data-driven approach

In the absence of data specifically on the number of sinks in the UK, I use multiple alternative data sources to achieve a rough estimate. In my approach, I used household and building data and estimated the average number of sinks per household and per non-domestic building type.

Method

Number of sinks = \((Households_N * 2.15) + (NonDomesticBuildings_N * 6) * MiscBuffer\)

Number of Households

Here, I multiply the number of households in the UK by 2.15. This is making the assumption that a typical household will have 2.15 sinks. This estimate was reached by assuming on average 90% of households have 2 sinks, 1 kitchen sink and 1 bathroom sink, whereas 10% have 3.5 sinks. This 10% was added to account for all household with more than 2 sinks.

Number of non-domestic buildings

Additional considerations were added to account for non-domestic buildings, such as shops, offices, warehouses etc. It is reasonable to assume that all buildings that have plumbing (i.e. sinks), also have an energy supply. Therefore I searched for survey data from energy suppliers on the number of business energy supplies and used this as an indicator for how many non-domestic buildings there are. A reliable report from the Non-Domestic National Energy Efficiency Data-Framework estimated the number of non-domestic buildings in England and Wales in 2020¹, and so these figures were used directly.

Shops make up 29% of the non-domestic buildings in England and Wales, followed by offices (20%), factories (14%), and Warehouses (12%). Based on these proportions of building types, we estimate an average of six sinks per non-domestic building.

Miscellaneous buffer

A 5% buffer was added to account for miscellaneous sinks such as those on boats, campsites, second homes etc.

How many households are there in the UK?

Figure 1. Number of households in UK by region

Total number of households in UK:

28,068,000

Data source: Office for National Statistics - Families and Households in the UK

How many non-domestic buildings in the UK?

Figure 2. Number of non-domestic buildings in England and Wales by category

Data source: Non-Domestic National Energy Efficiency Data-Framework (ND-NEED)

Total number of non-domestic buildings in England and Wales:

1,656,000

To estimate the number of non-domestic buildings in Scotland and Northern Ireland, I use the proportion of households in Scotland and Northern Ireland relative to England and Wales.

Scotland Households/England and Wales Households

2509000/24831000 = 0.08939005

Northern Ireland Households/England and Wales Households

728000/24831000 = 0.02593701

These ratios are multiplied to the number of non-domestic buildings in England and Wales and added to the total number of non-domestic buildings in England and Wales.

Total number of non-domestic buildings in UK:

1,871,878