Nadc drainage contractor: UK Drainage Accreditation Register
The UK Drainage Accreditation Register carries 1 published figure read from 1 source's own page, from 32,500 to 32,500 count, read 24 October 2026.
3 of the 11 named sources read in full publish a figure; 8 publish none, read 24 October 2026.
By scheme
| Breakdown | Median | Range | Sources |
|---|---|---|---|
| schemeCHAS (SSIP) | 32,500count | 32,500 to 32,500count | 1 |
| schemeNADC | 350certified | 350 to 350certified | 1 |
| schemeOnce For All (Constructionline) | 3,000organisations | 3,000 to 3,000organisations | 1 |
Every figure, with its source
One row per published figure: the figure as the source's own page publishes it, the page, and the day it was read. A figure that is not on a page we read is not on this one.
| Source | Figure | Breakdown | Read |
|---|---|---|---|
| CHAS | 32,500count | CHAS (SSIP) | 2026-10-24 |
| Constructionline | 3,000organisations | Once For All (Constructionline) | 2026-09-11 |
| National Association of Drainage Contractors | 350certified | NADC | 2026-10-11 |
The sentence each figure was read from (3)
- CHAS, read 2026-10-24:
Contractors can build their business on certification they’re proud of, while clients get fast access to over 32,500 verified, compliant contractors.
- Constructionline, read 2026-09-11:
Once For All Health & Safety is the go-to scheme for SSIP health and safety certification for over 3,000 organisations.
- National Association of Drainage Contractors, read 2026-10-11:
Over 350 certified members
Read in full, publishes no figure
8 named sources were read in full on the dates shown and print no usable figure. They are counted, never filled in.
- Water Jetting Association members directory, read 2026-09-11: read in full and no accepted figure on the page
- Water Jetting Association, joining, read 2026-09-11: every candidate on the page was refused
- Environment Agency register of waste carriers, brokers and dealers, read 2026-10-11: read in full and no accepted figure on the page
- Environment Agency public registers index, read 2026-09-11: read in full and no accepted figure on the page
- GOV.UK guidance, access the public register for environmental information, read 2026-09-11: read in full and no accepted figure on the page
- SEPA registered waste carriers and brokers, read 2026-10-11: read in full and no accepted figure on the page
- Companies House, National Association of Drainage Contractors, read 2026-09-11: read in full and no accepted figure on the page
- SafeContractor, read 2026-09-11: every candidate on the page was refused
Methodology
Every row is a verbatim sentence read from the named source's own page through our fetch service on the date shown, hash-pinned to the stored read (the sha of the page's visible text; the raw page is mirrored to R2).
3 of the 11 named sources that could be read published a usable figure; 8 published none and are recorded as not published, never filled in; 1 could not be read (blocked, dead or unreachable) and count nowhere.
The headline figures (median, minimum, maximum, quartiles) are over ONE figure per source in count (a source's median where its page yielded several accepted sentences), so N counts sources, never sentences; 14 candidate sentence(s) were refused by a reviewer with the reason recorded.
The fuller derivation this dataset is chartered to grow into (not yet what the figures above are; they are each source's own published figure as read): one row per contractor joined ACROSS schemes that each publish only their own members - the two trade associations, the three safety-scheme registers, and the statutory waste-carrier register a firm must hold to remove the waste - giving the count of firms holding more than one, by region and by scheme, and the share of firms advertising commercial drainage that appear on none.
Every scheme answers for itself; nobody joins them.
14 candidate sentences on these pages were refused by a reviewer; each refusal and its reason is recorded in the review ledger.
Sources (12)
- National Association of Drainage Contractors(the publisher's own terms; quoted for reporting and comment)
- Water Jetting Association members directory(the publisher's own terms; quoted for reporting and comment)
- Water Jetting Association, joining(the publisher's own terms; quoted for reporting and comment)
- Environment Agency register of waste carriers, brokers and dealers(the publisher's own terms; quoted for reporting and comment)
- Environment Agency public registers index(the publisher's own terms; quoted for reporting and comment)
- GOV.UK guidance, access the public register for environmental information(the publisher's own terms; quoted for reporting and comment)
- SEPA registered waste carriers and brokers(the publisher's own terms; quoted for reporting and comment)
- Companies House, National Association of Drainage Contractors(the publisher's own terms; quoted for reporting and comment)
- NADC Ireland branch(the publisher's own terms; quoted for reporting and comment)
- Constructionline(the publisher's own terms; quoted for reporting and comment)
- CHAS(the publisher's own terms; quoted for reporting and comment)
- SafeContractor(the publisher's own terms; quoted for reporting and comment)
Cite or embed this figure
The UK Drainage Accreditation Register carries 1 published figure read from 1 source's own page, from 32,500 to 32,500 count, read 24 October 2026.
3 of the 11 named sources read in full publish a figure; 8 publish none, read 24 October 2026.
UK Drainage Accreditation Register, scheme CHAS (SSIP): median 32,500 count across 1 source, read 24 October 2026.
UK Drainage Accreditation Register, scheme NADC: median 350 certified across 1 source, read 24 October 2026.
UK Drainage Accreditation Register, scheme Once For All (Constructionline): median 3,000 organisations across 1 source, read 24 October 2026.
Cite as: "commercialdrainagequotes.co.uk UK Drainage Accreditation Register", updated 2026-10-24, https://commercialdrainagequotes.co.uk/datasets/uk-drainage-accreditation-register/.
Download the CSV (3 rows, computed 2026-10-24)