Do I need a permit to discharge dewatering water from a construction site?

Under EPA's 2022 CGP, uncontaminated construction dewatering water is a covered discharge when handled under Part 2.4. State, Tribal and local rules may add requirements, and contaminated water needs other authorization.

How often must dewatering be inspected?

EPA's permit requires an inspection once per day on which dewatering water is discharged, with a report within 24 hours (Parts 4.3.2 and 4.6.3). Texas also requires daily observation on discharge days (Part III.F.7).

What is the turbidity benchmark for dewatering?

50 NTU, compared as a weekly average, for EPA CGP sites discharging dewatering water to sediment-impaired, Tier 2, 2.5 or 3 waters, or Lands of Exclusive Federal Jurisdiction. An exceedance triggers corrective action.

Can dewatering water go into a storm drain?

EPA's permit requires treatment through a sediment control first and allows no visual turbidity, floating solids, foam or sheen. Local rules for storm sewers also apply.

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Construction dewatering under a stormwater permit

Under EPA's 2022 Construction General Permit, uncontaminated water pumped from foundations, vaults and trenches is an allowed discharge if it is handled by the permit's dewatering rules: route it through a sediment control designed to prevent visible turbidity, discharge no floating solids, foam or sheen, infiltrate it on vegetated upland areas where feasible, and never use a receiving water as the treatment area. EPA 2022 CGP Part 1.2.2, 2.4 Each day water is discharged, the site is inspected and a report written within 24 hours. EPA 2022 CGP Part 4.3.2, 4.6.3 Where the discharge reaches sediment-impaired or high-quality waters, daily turbidity samples are compared weekly with a 50 NTU benchmark. EPA 2022 CGP Part 3.3

National guide. The rules cited are from EPA's 2022 Construction General Permit (as modified in 2025), checked October 20, 2026, which applies where EPA is the permitting authority. Most states issue their own permit with different details; check your state before relying on a number.

Sources last checked October 19, 2026. Prepared by our team led by Mohamed Elansary, PhD, with AI research tools. We are not a licensed engineering firm and do not seal plans.

General information; your permit text controls. Not legal advice and not engineering judgment. We make no promise of permit coverage, agency acceptance or compliance.

Do you need a separate dewatering permit

For many sites, no: EPA's permit lists uncontaminated construction dewatering water among the non-stormwater discharges it covers, when discharged under Part 2.4. EPA 2022 CGP Part 1.2.2 EPA notes operators may need extra steps to verify the water is uncontaminated, and should check Part 9 and any State, Tribal or local dewatering requirements. EPA 2022 CGP Part 1.2.2, footnote 7 Contaminated groundwater is outside that coverage. Florida's permit covers uncontaminated groundwater only after you complete Part VI of the NOI and keep documentation on site that the property is not a contaminated site and has none within 500 feet, or that DEP has confirmed remediation. FDEP CGP Part 3.4.2-3.4.4

EPA's dewatering controls

Part	Rule
2.4.1	Route water through a sediment control (for example a sediment trap or basin, or a pumped water filter bag) designed to prevent visual turbidity: a plume, or water that looks cloudy, opaque or visibly different. EPA 2022 CGP Part 2.4.1, footnote 56
2.4.2	No visible floating solids or foam. EPA 2022 CGP Part 2.4.2
2.4.3	No visible sheen or oily deposits; use an oil-water separator or cartridge filter if the water contains or is expected to contain oil or grease. EPA 2022 CGP Part 2.4.3
2.4.4	Infiltrate on well-vegetated upland areas where feasible; receiving waters may not be part of the treatment area. EPA 2022 CGP Part 2.4.4
2.4.5	Discharge onto stable surfaces (vegetation, clean filter stone, geotextile); no filter bags on steep slopes; velocity dissipation at discharge points. EPA 2022 CGP Part 2.4.5
2.4.6	Haul backwash water away or return it to the start of treatment. EPA 2022 CGP Part 2.4.6
2.4.7	Replace or clean filter media when the pressure differential reaches the manufacturer's specification. EPA 2022 CGP Part 2.4.7

EPA's permit defines dewatering as draining accumulated stormwater or groundwater from foundations, vaults, trenches or similar points of accumulation. EPA 2022 CGP Part 2.4, footnote 55

Daily inspection and report

On each day dewatering water is discharged, inspect during the discharge. EPA 2022 CGP Part 4.3.2 Within 24 hours, record the date, the inspectors' names and titles, approximate start and end times, the estimated rate in gallons per day, whether a plume, suspended solids, unusual color, odor, decreased clarity, foam or sheen was seen at the discharge point, and the other items Part 4.6.3 lists. EPA 2022 CGP Part 4.6.3

Turbidity sampling for sensitive waters

If dewatering water reaches a water impaired for sediment, a Tier 2, 2.5 or 3 water, or a water within Lands of Exclusive Federal Jurisdiction, EPA's permit adds monitoring. EPA 2022 CGP Part 3.3

At least one sample each day of discharge, at every discharge point, after treatment, read on a turbidity meter using a Part 136 method (for example 180.1 or 2130), with a calibration check before each day's use. EPA 2022 CGP Part 3.3.1
Compare the weekly average (Monday to Sunday) with the 50 NTU benchmark, or an alternate benchmark EPA has approved. An exceedance is not a violation, but it triggers corrective action under Part 5.2.2. EPA 2022 CGP Part 3.3, 3.3.2, 3.3.3
Report weekly averages through EPA's NeT system within 30 days after each quarter: by April 30, July 30, October 30 and January 30. EPA 2022 CGP Part 3.3.4, Table 3

How states differ

Permit	Dewatering rule
Texas TXR150000	Discharges from dewatering trenches and excavations are prohibited unless managed by controls that address sediment and prevent erosion. TXR150000 Part IV.C Controls are observed and evaluated once per day of discharge, with a report within 24 hours that includes the start and end times and the estimated rate in gallons per day. TXR150000 Part III.F.7
Florida CGP	Uncontaminated groundwater only, with NOI Part VI and on-site documentation; no floating solids or foam; discharge to vegetated upland areas when feasible, or to the project's permitted stormwater system; dewatering BMPs go in the SWPPP's dewatering section. FDEP CGP Part 3.4.1-3.4.6
Mississippi MSR10	Construction dewatering water is an allowed discharge when handled under ACT5 T-11, whose items track EPA's: sediment control, no solids, foam or sheen, upland infiltration, stable surfaces, velocity dissipation, backwash handling and filter media changes. MSR10 ACT2 T-3(L); ACT5 T-11(A)-(H)
Washington CSWGP	Turbid foundation, vault and trench water goes to a sediment trap or pond with BMPs; clean, non-turbid water such as well-point groundwater may go to surface waters if it causes no erosion or flooding, and must not be routed through stormwater sediment ponds. Highly turbid or contaminated water is handled separately. CSWGP S9.D.10

Check your state hub for the permit that applies: Alaska, Arizona, Arkansas, Colorado, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kentucky, Louisiana, Massachusetts, Michigan, Mississippi, Nebraska, Nevada, New Hampshire, New York, North Dakota, Ohio, Oklahoma, Oregon, South Carolina, South Dakota, Texas, Utah, Washington, West Virginia. Related: construction stormwater BMPs by type, sediment basins, SWPPP inspection requirements.

Our plans describe the dewatering controls and the daily inspection record for the permit that covers your site. We do not sample, test water or design treatment systems.

What this page does not cover

Contaminated groundwater, treatment system design, chemical treatment, water sampling and laboratory work, and local sewer or groundwater permits.

Have it written for you

SWPPP Desk prepares site-specific SWPPPs from your drawings for construction sites in the states we cover (coverage by state), for a fixed price, delivered the next business day after your inputs are complete. Small site (1 to under 5 acres): $449. Large site (5 acres or more): $749. Background: all guides.

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