Londonderry, NH
Lead detected, under the action levels
Latest 90th-percentile lead: 4 ppb (monitoring period 2015-2017). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Londonderry at a glance
Londonderry serves about 6,255 people through 1,791 service connections, which makes it a medium-sized system under EPA's size classes. It is privately owned and draws surface water, in Rockingham County, New Hampshire. EPA system ID: NH1391010. Ask the utility on your bill for your address in their service line inventory.
Londonderry's lead record
That is up 3 ppb from 1 ppb in the period ending 2017. The highest 90th-percentile result EPA holds for Londonderry is 4 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2017 | 4 ppb |
| 2017 | 1 ppb |
| 2016 | 0 (not detected) |
Where this result ranks
Of the 124 New Hampshire systems with a lead result, the median latest reading is 16 ppb; 62 are over 15 ppb right now and 64 have gone over at some point. Londonderry's 4 ppb sits at the 42nd percentile in New Hampshire and the 88th nationally (higher means more lead).
Nearby utilities
185 other systems share Rockingham County; 11 of them have a higher latest lead result than Londonderry. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Portsmouth Water Works | 33,000 | 0 (not detected) |
| Salem Water Dept | 21,080 | 2 ppb |
| Derry Water Dept | 17,528 | 0 (not detected) |
| Seabrook Water Dept | 14,000 | 3 ppb |
| Exeter Water Dept | 12,236 | 0 (not detected) |
| Pease Trade Port | 9,900 | 0 (not detected) |
| Hampstead Area Water | 7,153 | 2 ppb |
| Newmarket Water Works | 5,030 | 2 ppb |
| Rye Water Dist | 4,300 | 0 (not detected) |
| Raymond Water Dept | 3,300 | 1 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Nashua, NH may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Londonderry whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. The action level is dropping - the 10 ppb rule from 2027.