Table 1. Information on Cities, Areas Surveyed, and Associated Population Based on the NASA SEDAC Population Estimation Service.

city name	surveyed by laboratory # in year	description of main areas included in the surveys	land area included in the analysis (km2)	population in the analyzed area (million)	population density (thousands/km2)	pipeline material (PVC + PE/steel/cast iron/other)
(BAR) Barcelona, Spain	8 in 2018/2019	mostly within city limits	223	2.32	10.4	85%/13%/2%/0%
(BIR) Birmingham, United Kingdom	5 in 2019	urban region included	91	0.42	4.6	65%/6%/14%/16%
(BUC) Bucharest, Romania	3, 5 in 2019	some outskirts included	159	1.29	8.1	52%/48%/0%/0%
(GRO) Groningen, The Netherlands	6 in 2018	focus mostly on city of Groningen	73	0.14	2.0	80%/15%/3%/2%
(HAM) Hamburg, Germany	3 in 2018/2020	North Elbe	737	1.46	2.0	54%/44%/2%/0%
(KAT) Katowice, Poland	4 in 2018	surrounding urban areas included	793	1.29	1.6	40%/60%/0%/0%
(LON) London, United Kingdom	5 in 2018/2019	includes greater London metropolitan area	2029	9.74	4.8	65%/6%/14%/16%
(MUN) Munich, Germany	9 in 2018/2019	focus on city center	199	0.90	4.5	54%/44%/2%/0%
(PAR) Paris, France	7 in 2018/2019	includes Billancourt and Issy les Moulineaux	225	4.00	17.8	70%/26%/3%/1%
(SWA) Swansea, United Kingdom	5 in 2019	includes suburbs	123	0.19	1.6	65%/6%/14%/16%
(TOR) Toronto, Canada	1, 2 in 2018/2019	includes neighboring suburbs	562	2.25	4.0	N/A
(UTR) Utrecht, The Netherlands	3 in 2018/2019	inside the highway ring	48	0.16	3.4	80%/15%/3%/2%