How we check costs

Prices on this site come from published sources we have opened and read. We don’t guess, average our own estimates or copy figures from other blogs without finding the original.

Where prices come from

We use four kinds of source, in this order of preference:

1. Published tariffs from councils and water companies, such as Scottish Water’s de-sludging charges or a council emptying service. These are real prices anyone can pay.
2. National cost guides that publish their method and date, such as Checkatrade’s cost guides.
3. Specialist firms that publish their own prices, such as survey fees.
4. Regulators’ figures, such as SEPA’s registration fee.

Every price on the site names its source and links to it.

How we present them

• Ranges, not single numbers. Your tank, access and postcode will change the price.
• A checked date. Every price box says when we last checked the source. Current figures were checked in October 2026.
• Where sources disagree, we say so. Drainage field replacement is a good example: one national guide and one specialist firm give very different ranges, and we show both.
• VAT. We say whether a source includes VAT where it tells us. Where it doesn’t, treat the figure as unconfirmed.
• Our own arithmetic is labelled. If we multiply a published price, for example to show a year of cesspit emptying, we say it’s an illustration.

What we don’t do

• We don’t take payment to include or change a price.
• We don’t publish “average” figures we can’t trace to a source.
• We don’t quote prices from pages that have since gone offline.

How often we re-check

We aim to re-check every price at least once a year and whenever a council or water company publishes a new tariff. The date on each price box tells you when we last did.

Found a better source?

If you’ve got a published price list, or a recent quote you think shows our ranges are off, email hello@offmainsdrainage.co.uk.