Data report · 2026

Pennsylvania Water Damage Risk Index

Where in Pennsylvania is a house most likely to take on water? We combined Census housing age with ten years of daily weather for 67 of Pennsylvania's 67 counties to rank them.

Highest index

Schuylkill

Score 78 of 100

Most pipe-freeze nights

Potter

58 nights ≤ 20°F a year

Oldest housing

Philadelphia

65% built before 1960

Most heavy-rain days

Monroe

13.1 days ≥ 1 inch a year

< 4040–4747–5353–60≥ 60 index (0–100)

Key findings

The five highest-scoring counties are Schuylkill, Lackawanna, Luzerne, Philadelphia, Carbon. Each combines old housing with harsher-than-average winters or frequent downpours.
Philadelphia County has the oldest housing in the state, with 65% of homes built before 1960, against a county median of 42%.
Potter County averaged 58 nights a year at 20°F or colder, the most of any county in the data. The county median is 37.
Chester County has the newest housing, with 26% of homes built since 2000, which pulls its index down even where winters are cold.

Weather: NOAA nClimGrid-Daily county averages, 2015–2024. Housing: ACS 2020-2024.

All counties

Select a column header to sort.

Rank	County	Index	Freeze nights	Pre-1960 homes	Heavy-rain days	Muggy nights
1	Schuylkill	78	37	61%	10.9	26
2	Lackawanna	74	48	55%	9.2	12
3	Luzerne	70	46	50%	9.6	14
4	Philadelphia	67	16	65%	10.1	72
5	Carbon	65	46	41%	12.2	12
6	Northumberland	64	34	55%	7.5	28
7	Cambria	63	46	57%	6.7	9
8	Delaware	63	16	58%	9.5	70
9	Lycoming	62	46	48%	7.7	11
10	McKean	62	55	59%	5.7	5
11	Northampton	62	35	41%	11	31
12	Lehigh	61	32	42%	11	35
13	Bradford	60	50	44%	7.1	11
14	Sullivan	60	56	39%	9.4	6
15	Berks	57	29	43%	10.1	41
16	Cameron	57	51	51%	5.8	6
17	Warren	57	50	51%	5.9	8
18	Wyoming	57	46	36%	10.1	14
19	Columbia	56	40	39%	9.6	19
20	Fayette	56	34	51%	6.9	16
21	Mifflin	56	32	51%	7	29
22	Susquehanna	56	54	35%	8.9	9
23	Armstrong	55	38	51%	6.6	15
24	Elk	55	49	48%	6.3	8
25	Clinton	54	46	43%	6.8	12
26	Blair	53	37	54%	5.9	16
27	Monroe	53	49	17%	13.1	9
28	Pike	53	52	15%	10.5	9
29	Lebanon	51	27	39%	10.4	46
30	Somerset	51	45	47%	6.8	5
31	Venango	51	44	51%	5.6	12
32	Lawrence	50	35	56%	5.3	18
33	Potter	50	58	41%	6.1	3
34	Wayne	50	55	26%	9.4	6
35	Beaver	49	31	55%	5.8	21
36	Westmoreland	49	32	44%	7	21
37	Allegheny	48	28	55%	5.9	30
38	Erie	48	42	46%	5.6	19
39	Tioga	48	55	41%	5.8	3
40	Jefferson	47	46	49%	4.8	9
41	Union	47	37	37%	7.3	25
42	Clearfield	46	47	43%	5.6	9
43	Dauphin	46	28	39%	8.9	45
44	Montour	46	36	33%	7.8	25
45	Greene	45	29	50%	6.1	22
46	Mercer	44	41	47%	5.2	14
47	Crawford	43	44	44%	5.2	12
48	Montgomery	43	22	37%	9.3	54
49	Snyder	43	32	37%	7.2	31
50	Indiana	42	39	39%	6.5	12
51	Centre	41	42	27%	7.3	15
52	Clarion	41	45	43%	5.4	9
53	Huntingdon	41	32	39%	6.6	25
54	Bucks	40	25	30%	9.9	46
55	Chester	40	23	23%	10.6	50
56	Juniata	39	29	37%	6.8	35
57	York	39	23	33%	8.8	48
58	Lancaster	38	24	33%	8.7	48
59	Bedford	37	34	39%	5.9	15
60	Perry	37	28	33%	7.2	41
61	Adams	34	26	29%	8.2	41
62	Butler	34	38	30%	6.4	15
63	Cumberland	34	26	30%	7.3	45
64	Forest	34	49	32%	5.5	8
65	Washington	34	29	44%	4.7	23
66	Franklin	31	28	30%	6.7	35
67	Fulton	30	30	32%	6.3	24

Methodology

For each county with weather data, we convert four factors to a percentile rank among those counties (0 = lowest, 100 = highest), then take a weighted average:

Pipe-freeze nights (nights ≤ 20°F / yr), weight 30%
Homes built before 1960 (% of homes), weight 30%
Heavy-rain days (days ≥ 1 in / yr), weight 25%
Muggy nights (nights ≥ 65°F / yr), weight 15%

Freezing weather and old plumbing get the most weight because burst and failing supply lines are among the most common causes of household water damage. Heavy rain drives basement flooding and sewer backups, and warm, muggy nights mark the humid air that lets mold follow. The index is relative: a low score means lower risk than other Pennsylvania counties, not no risk.

Limits: weather values are county-wide averages, so hollows, ridges and lakeshores can differ; ACS housing figures are survey estimates; the index doesn't account for floodplains, soil, or local sewer systems. Full details on our data sources page.

Cite this data

You're welcome to use these figures with attribution. Suggested citation:

Local Water & Mold, "Pennsylvania Water Damage Risk Index 2026," https://localwatermold.com/pennsylvania/pennsylvania-water-damage-risk/. Data: U.S. Census Bureau ACS 2020-2024; NOAA nClimGrid-Daily 2015–2024.