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Bottle gully vs back inlet

Updated: 23 October 2026

The two black pots in the search results are almost the same photograph, and the downpipe on your wall is not almost the same pipe. Bottle gully vs back inlet is one decision: does the water fall through a grid from a shoe, or does the pipe enter the body at the wall? In this set that is UK Plastics B08YKJ44RP at £12.47 against UK Plastics B08YNXYSN1 at £12.99, both 110 mm and plain ended, on the [rain gully comparison](/hub/diy-supplies/rain-gully). Prices are the saved amazon.co.uk figures and they move. A qualifying purchase can earn a commission at no extra cost to you. Neither title is a FloPlast D510 or D540. Updated 22 October 2026.

The two black pots in the search results are almost the same photograph, and the downpipe on your wall is not almost the same pipe.

Our top picks

UK Plastics UK Plastics single-inlet bottle gully

Best overall

UK Plastics UK Plastics single-inlet bottle gully
9.0/10about £12.47
View offer
n/a Horizontal bottle gully 305 x 155 mm

Best value

n/a Horizontal bottle gully 305 x 155 mm
7.3/10about £33.44
View offer
UK Plastics UK Plastics back-inlet bottle gully

Alternative

UK Plastics UK Plastics back-inlet bottle gully
7.0/10about £12.99
View offer
On this page
  1. 1.Open grid under a shoe
  2. 2.Sealed pipe at the wall
  3. 3.Using a back inlet with nothing in the socket
  4. 4.When to choose neither

Open grid under a shoe

Choose the single inlet when a shoe can drop through the grate. B08YKJ44RP is £12.47, 4.4 from 48, with a circular grid and no diameter printed. Kalsi Plastics says: if the downpipe drops onto the grid, use a bottle gully. The shoe has to land on that grid. A back inlet does not aim a shoe that misses. One UK review said the diameters were way off and the buyer returned it. Another said they were correct. The plastic was also called thin enough to crack if forced. The extra 52 pence for the back-inlet body will not correct a bad diameter.

Sealed pipe at the wall

Choose the back inlet when the pipe enters the body at the wall. B08YNXYSN1 is £12.99, 4.3 from 17, with a 180 mm circular grid and a plain-ended 110 mm outlet. Brett Martin’s fork is a shoe into the gully, or an adaptor and a bend into a back inlet. The 180 mm figure is the grid, not the pipe. The listing’s 4 inch is the trade name for 110 mm. You still need a coupler if your pipe has no socket. FloPlast says remove the plug on its own back inlet and do not drill the body. The bullets for this ASIN do not mention a plug. Do not drill either pot to make an inlet.
UK Plastics UK Plastics single-inlet bottle gully

Testsieger

UK Plastics UK Plastics single-inlet bottle gully
9.0/10about £12.47
View offer

Using a back inlet with nothing in the socket

Leave a back-inlet socket open and silt can enter, and water can leave by a path that is not the 110 mm drain. One UK review of B08YNXYSN1 said a spare port needs a blanking plug at about £5. The bullets do not list a plug. Treat that £5 as the reviewer’s figure. Truly PVC, J C Tye and Pipetek sell rear-inlet kits with a socket plug. Those catalogues are not this ASIN. If the downpipe uses the socket, buy the adaptor. If the socket stays empty, fit the plug before you backfill. The top grid still takes yard water. It does not replace the plug.

When to choose neither

Neither pot suits a shallow invert. Two UK reviews of B0120PT0I0 at £33.44 say a normal bottle would not fit that 305 × 155 mm body. Jacking a tall pot up is how the top ends up inside 150 mm of the damp-proof course. That 150 mm figure is a merchant note. Setting the pot is on how to install a bottle gully. Neither belongs in a flat roof, and neither names BS 4660. If you need that standard, or a plug printed in the contents, leave both UK Plastics rows.

Common questions

Which one if the downpipe already has a shoe?
The single-inlet gully, B08YKJ44RP at £12.47. The shoe should discharge through the open grid. A back inlet does not aim the shoe for you, and an unused socket on that body has to be plugged. Line the shoe up with the grate or the water will splash onto the paving even if the pot is the right type.
Which one if the pipe goes through the wall?
The back-inlet gully, B08YNXYSN1 at £12.99, with an adaptor into that socket rather than a shoe in mid-air. Brett Martin describes that connection. The grid is stated at 180 mm and the outlet is 110 mm plain ended, so you still need a coupler unless your pipe brings the socket. Do not drill the single-inlet pot to copy this.
Can I use a back inlet as a normal open gully?
Only if every socket you are not using is blanked. The top grid can take water from a shoe or from the yard, which is why the two bodies look alike. An open boss is a leak and a silt path. This listing does not say a plug is included. One UK review said you need one, at about £5 in that buyer’s account.
Is the 180 mm grid the outlet size?
No. On B08YNXYSN1, 180 mm is the circular grid in the bullets. The outlet is 110 mm, also described as 4 inch. The single-inlet listing does not print a grid diameter at all. Ordering either pot because you want a pipe wider than 110 mm will not change the spigot in the box.
Are these two the same plastic and the same standard?
Both are UK Plastics, both are plain-ended 110 mm bottle gullies, and neither title names BS 4660 or BS EN 1401-1. Material is not printed on either listing, so you cannot claim they are the same polymer from the page. They are the same family of pot with a different inlet. A FloPlast code on a merchant site is a different product.
When is neither the right part?
When the drain is too shallow for a tall bottle, when the water is on a flat roof, or when you need a stated British Standard and a plug listed in the box. The horizontal gully is the shallow-ground option at £33.44. The DN70 listing is the roof option. A car over the grid is a reason to leave both plastic covers, because neither prints a vehicle class.

Related pages

Rain gully buying guide

Rain gully

Best bottle gully for a shoe, wall or shallow drain

Flat roof gully with a leaf guard and a visible overflow

How to install a bottle gully so the grid stays flush

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Scoring method dated 22 October 2026. Updated 23 October 2026.

  1. Approved Document H (England), 2015 (retrieved 22 October 2026)
  2. Scottish Technical Handbook 3.6 (retrieved 22 October 2026)
  3. FloPlast underground drainage (retrieved 22 October 2026)
  4. FloPlast underground drainage FAQs (retrieved 22 October 2026)
  5. Harmer roof brochure (retrieved 22 October 2026)
  6. Northern Ireland roof drainage (retrieved 22 October 2026)
  7. Brett Martin rainwater FAQ (retrieved 22 October 2026)
  8. NHBC Standards 2025, chapter 5.3 (retrieved 22 October 2026)