Intro
When standard-length bits bottom out before they reach the far side of a thick foundation wall, structural column, or multi-layer masonry construction, a long-reach SDS-max bit is the answer. A 25 mm diameter bit stretching nearly a metre in length lets you drill all the way through in a single pass — no drilling from both sides, no misaligned holes meeting in the middle, no wasted time. For contractors installing through-bolts in thick concrete, running pipe penetrations through basement walls, or anchoring structural steel to deep foundations, a long-reach carbide-tipped bit is not a luxury — it is the difference between finishing the job in one operation and spending the afternoon improvising extensions and drilling from awkward angles.
Generalities
Dewalt's DW5820 is an SDS-max carbide-tipped masonry bit with a 25 mm diameter and an overall length of 933 mm — over 36 inches. Manufactured in Germany, it features a black oxide finish and a 118-degree carbide cutting tip designed for hard concrete. The extreme length places it in a specialist category: it is not the bit you reach for when mounting a bracket, but the one you need when drilling through a 600 mm retaining wall or a multi-wythe brick pier. With a 4.9 out of 5 star average from 25 reviews, it is one of the highest-rated bits in its class.
This review examines the design, performance, and applications of this long-reach SDS-max bit — covering what makes it effective in deep-hole drilling and the professional scenarios where its length is essential rather than merely convenient.
Description
The bit delivers a 25 mm (1 inch) diameter hole through concrete and masonry, with an overall length of 933 mm (approximately 36 inches) and a usable drilling depth of roughly 780 mm (31 inches). The tungsten carbide tip is brazed onto a hardened steel body with a black oxide finish that provides some corrosion resistance. The bit weighs approximately 1.76 kg (3.88 pounds) — substantial enough that the hammer supporting it must be capable of handling the combined weight during overhead or horizontal drilling.
The cutting tip uses a 118-degree angle geometry, which balances sharp penetration against tip durability — steeper than some masonry bits, reflecting the bit's design intent for hard concrete rather than soft brick or block. The tip has a centring point to start holes accurately, preventing the bit from wandering across the surface at the beginning of the cut — especially important at this length, where even a small angular deviation at the start compounds into a significant positioning error by the time the bit reaches full depth.
The spiral flute body clears drilling dust along the full 933 mm length of the bit. In a hole this deep, dust evacuation is the critical performance factor — a clogged flute 700 mm into the hole will stop progress completely and can overheat the carbide tip. Regular withdrawal to clear accumulated dust is recommended for deep holes, even with an efficient flute design. The bit requires an SDS-max rotary hammer with at least 8 joules of impact energy to drive a 25 mm bit through hard concrete at a reasonable rate.
Manufactured in Germany, the bit carries Dewalt's quality standards and is backed by their warranty. The 25 customer reviews averaging 4.9 out of 5 stars represent exceptional satisfaction for a consumable accessory — users consistently highlight the bit's ability to drill deep holes quickly and the durability of the carbide tip in abrasive concrete. At its price point, this is a professional investment justified by jobs where the only alternative to a long bit is coring from both sides or using a much more expensive core drill rig.
The universal SDS-max shank ensures compatibility with all major brands of rotary hammer. The bit operates exclusively in rotary hammer mode — it must rotate to clear debris and should not be used in hammer-only or rotary-only configurations. For structural contractors, foundation specialists, and heavy civil engineering crews, this long-reach bit represents a specialist tool that solves a specific problem: drilling deep, large-diameter holes through thick concrete in a single operation.
Pros and cons
Pros
- 933 mm overall length with approximately 780 mm usable drilling depth reaches through thick foundation walls, structural columns, and multi-wythe masonry in a single pass — no drilling from both sides or joining misaligned holes
- 4.9 out of 5 stars from 25 reviews is near-perfect user satisfaction — exceptionally high for a consumable accessory, reflecting genuine performance and durability in demanding applications
- Manufactured in Germany with Dewalt's quality control — the 118-degree carbide tip is precisely brazed and the black oxide finish provides corrosion resistance for tools that may be stored between jobs
- 25 mm diameter covers common large structural fixing sizes — M20 and M24 through-bolts, chemical anchor capsules, and pipe sleeves for plumbing and electrical services
- Spiral flute design manages dust clearance over the full length — critical for deep holes where dust must travel nearly a metre to escape
- Universal SDS-max shank — compatible with Bosch, Makita, Hilti, Milwaukee and all other SDS-max rotary hammers
Cons
- At 1.76 kg, the bit itself is heavy — combined with an SDS-max rotary hammer, the total weight makes sustained overhead drilling extremely demanding physically
- The extreme length makes the bit unwieldy for shallow holes — this is a specialist tool for deep drilling, not an all-purpose 25 mm bit for standard anchor installations
- Requires a powerful SDS-max hammer — 8 joules or more — and is completely incompatible with SDS-plus tools, limiting its use to contractors who already own heavy rotary hammers
- The price reflects the length and engineering — a significant investment for a single consumable bit that only makes financial sense for regular deep-drilling applications
Use cases
This long-reach 25 mm SDS-max carbide-tipped bit is designed for specialist contractors who need to drill deep holes through thick concrete and masonry — foundation walls, structural columns, retaining structures — where standard-length bits cannot reach all the way through.
Through-Foundation Drilling
Drilling all the way through thick concrete foundation walls for plumbing waste pipes, water mains, electrical service entries, and gas lines. The 933 mm length reaches through the deepest residential and light commercial foundations in a single pass, eliminating the need to core drill from both sides and risk misaligned holes.
Structural Column Penetrations
Drilling through reinforced concrete columns and beams for through-bolts, tension rods, and structural connections. The bit's length accommodates the full width of large columns, and the 25 mm diameter is sized for the M20 and M24 high-strength bolts used in structural steel connections.
Retaining Wall Drainage and Weep Holes
Installing drainage pipes and weep holes through thick retaining walls, basement walls, and below-ground structures. Deep holes require a long bit, and the clean cut reduces the time needed to seal around the penetration against water ingress.
Multi-Wythe Masonry Penetrations
Older industrial buildings and civil structures often have walls built from multiple layers of brick or block with cavities between them — total thicknesses of 600 mm or more. The long-reach bit drills through the entire wall assembly in one operation.
Deep Embedment Anchor Installation
Installing chemical anchors and through-bolts at embedment depths beyond the reach of standard-length bits. The 25 mm diameter and long reach allow deep anchoring for heavy machinery, structural bracing, and seismic restraint systems where shallow fixings would not meet the load requirements.